PSA was monolothic, now split, with new features, like
a DB-backed partial pipeline. FB OAuth2 version also upped.

Partial pipelines don't get cleared except when necessary.
They persist for special cases like change of browser while
still mid-pipeline (i.e. email validation step).

Refactor, cleanup, and update of a lot of small things as well.

PLEASE NOTE the new `social_auth_partial` table.

This makes it possible to refer to multiple book from a single app.

This also means that Open edX branches will be able to pass bok-choy
tests (at least if the books have already been built.)

2. Update COMPREHNSIVE_THEME_DIR to COMPREHENSIVE_THEME_DIRS
3. Update paver commands to support multi theme dirs
4. Updating template loaders
5. Add ENABLE_COMPREHENSIVE_THEMING flag to enable or disable theming via settings
6. Update tests
7. Add backward compatibility for COMPREHEHNSIVE_THEME_DIR

This reverts commit a796b563.

Conflicts:
	lms/envs/common.py
	openedx/core/djangoapps/theming/models.py
	pavelib/assets.py
	pavelib/paver_tests/test_assets.py

ziafazal: improvements need for multi-tenancy
ziafazal: fixed broken tests
ziafazal: no need to add setting in test.py
ziafazal: added hostname validation
ziafazal: changes after feedback from mattdrayer
ziafazal: fixed branding and microsite broken tests
ziafazal: make STATICFILES_DIRS to list
ziafazal: added theme directory to mako lookup for tests
ziafazal: added more protection in test_util
saleem-latif: Enable SCSS Overrides for Comprehensive Theming
saleem-latif: Incoporate feedback changes, Correct test failures, add tests and enable theming for django templates
saleem-latif: Correct errors in python tests
mattdrayer: Fix invalid release reference
mattdrayer: Update django-wiki reference to latest release
saleem-latif: Update Theme storages to work with Caching, Pipeline and collectstatic
saleem-latif: Incorporate feedback changes
mattdrayer: Pylint violation fix
mattdrayer: Fix broken pavelib test

This reverts commit 954dae58.

ziafazal: improvements need for multi-tenancy
ziafazal: fixed broken tests
ziafazal: no need to add setting in test.py
ziafazal: added hostname validation
ziafazal: changes after feedback from mattdrayer
ziafazal: fixed branding and microsite broken tests
ziafazal: make STATICFILES_DIRS to list
ziafazal: added theme directory to mako lookup for tests
ziafazal: added more protection in test_util
saleem-latif: Enable SCSS Overrides for Comprehensive Theming
saleem-latif: Incoporate feedback changes, Correct test failures, add tests and enable theming for django templates
saleem-latif: Correct errors in python tests
mattdrayer: Fix invalid release reference
mattdrayer: Update django-wiki reference to latest release

Comprehensive theming did not work with django templates (used by course wiki).

The reason it didn't work was that in order for the theme to work, theme template folder
has to be added to django template dirs setting *before* django startup.
After django startup, modifying `settings.DEFAULT_TEMPLATE_ENGINE['DIRS']` has no effect,
because at that point the template engine is already initialized with a copy of the
template dirs list.

Instead of running the theme startup code as an autostartup hook, we manually run it
*before* `django.setup()`. This is fine because theme startup code doesn't have to do
anything else besides modifying some settings and doesn't actually need django to be
initialized.

Adding the declaration of the settings object to openedx.conf to be able to import it from a nicer location

Resolving quality violations

Merging dicts with the settings definition when they exist in the microsite configuration

Using a cache to improve the perfomance of quering any dictionary in the microsite definition

Ignoring the invalid-name pylint warning since the names must be kept thsi way to stay the same as the ones in django.
Removing the default dict argument as per https://docs.python.org/2/tutorial/controlflow.html#default-argument-values

Extracting the implementation of the microsite to a selectable backend.

Leaving the function startup.enable_microsites for backwards compatibilityy

Adding a database backend

Using a cache to improve the perfomance of quering any dictionary in the microsite definition.
Changed the database backend so that it extends the settings file backend and removed all the unnecessary methods.

Using the backend provider for the get_dict function

some tweeks and some initial unit tests

Using getattr as a function insteal of calling the underlying __getattr__ directly

Adding an ModelAdmin object for the microsite model in the django-admin panel

refactor enable_microsites()

consolidate/refactor some shared code

add config to aws.py and add migration files

fix tests

Changes to get the backends to run after the refactor

add archiving capabilities to microsites. Also make a few notes about performance improvements to make

fix tests

Making the query to find if microsites exist in the database faster

add ORG to microsite mapping tables and some performance improvements

allow for Mako templates to be pulled from the database

fix tests

For the database template backend the uri of the template does not use the filesystem relative path

Fixing pylint violations

Added caching of the templates stored in the database

Fixing pylint errors

fix pylint

Clearing the cache on model save

Fixing pylint errors

rebased and added test coverage

rebased cdodge/microsite-improvements branch with master and added test
coverage

added missing migration

fix quality violations

add more test coverage

mattdrayer: Add microsite_configuration to cms.INSTALLED_APPS

added microsite settings to cms/envs/test.py

run session cookie tests only in LMS

fixed broken tests

putting middleware changes back

Preventing the template_backend to be called on requests which have no microsite

changes to address feedback from mjfrey

changed BaseMicrositeBackend to AbstractBaseMicrositeBackend

changes after feedback from mattdrayer

fixed broken tests and quality violations

Allowing the backend to handle the enable_pre_startup routine

Typos and docstrings

Adressing feedback

Fixing python tests

add comment to explain why we need enable_microsites_pre_startup()

Stripping the leading / for the django_templates finder

Enabling the microsite configurations before running django.setup()

Adding only the templates directory before startup

Adding the missing overrides file at the django templates main

Using the comp_theming way of overriding css

Adding test for the microsite_template_path filter

Please note that this is a squshed commit and the work of:
Symbolist, macdiesel, nedbat, doctoryes, muzaffaryousaf and muhammad-ammar

* The LMS now also monkey-patches
  xmodule.x_module.descriptor_global_handler_url and
  xmodule.x_module.descriptor_global_local_resource_url so that we can
  get LMS XBlock URLs from the DescriptorSystem. That functionality is
  needed in the block transforms collect() phase for certain XModules
  like Video. For instance, say we want to generate the transcripts
  URLs. The collect phase is run asynchronously, without a user context.

* The URL handler monkey-patching is now done in the startup.py files
  for LMS and Studio. Studio used to do this in the import of
  cms/djangoapps/contentstore/views/item.py. This was mostly just
  because it seemed like a sane and consistent place to put it.

* LmsHandlerUrls was removed, its handler_url and local_resource_url
  methods were moved to be top level functions. The only reason that
  class existed seems to be to give a place to store course_id state,
  and that can now be derived from the block location.

* To avoid the Module -> Descriptor ProxyAttribute magic that we do
  (which explodes with an UndefinedContext error because there is no
  user involved), when examining the block's handler method in
  handler_url, I made a few changes:

** Check the .__class__ to see if the handler was defined, instead of the
   block itself.

** The above required me to relax the check for _is_xblock_handler on the
   function, since that will no longer be defined.

90% of this goes away when we kill XModules and do the refactoring we've
wanted to do for a while.

* Upgrade edx-submissions
* Upgrade edx-ora2
* Upgrade edx-val
* Upgrade edx-proctoring
* Update all edx-platform code that depends on DRF, including:
  - auth_exchange
  - cors_csrf
  - embargo
  - enrollment
  - util
  - commerce
  - course_structure
  - discussion_api
  - mobile_api
  - notifier_api
  - teams
  - credit
  - profile_images
  - user_api
  - lib/api (OAuth2 and pagination)

* Upgrade edx-submissions
* Upgrade edx-ora2
* Upgrade edx-val
* Upgrade edx-proctoring
* Update all edx-platform code that depends on DRF, including:
  - auth_exchange
  - cors_csrf
  - embargo
  - enrollment
  - util
  - commerce
  - course_structure
  - discussion_api
  - mobile_api
  - notifier_api
  - teams
  - credit
  - profile_images
  - user_api
  - lib/api (OAuth2 and pagination)

Wrap 3rd Party Auth Pipeline with Segment enabled checks

This is a squash of 38 commits ending with
5b080f979d692804452400ac5bed9b17c50b001e

This makes these files importable, and puts them into the new best guess
as to where files should live.

This commit pulls in changes from #4487 that implements keyword
substitution for bulk emails. With these changes, an instructor can
include keywords in their bulk emails which will be automatically substituted
with the corresponding value for the recepient of the email. Keywords are
of the form %%keyword%%, and the keywords implemented in this commit include:

%%USER_ID%% => anonymous_user_id
%%USER_FULLNAME%% => user profile name
%%COURSE_DISPLAY_NAME%% => display name of the course
%%COURSE_END_DATE%% => end date of the course

Client-side validations have also been implemented to ensure that only emails
with well-formed keywords can be sent.
The architecture is designed such that adding in new keywords in the future
would be relatively straight-forward.