Fetched Programs and Program details from Course Discovery service for all sites and stored the uuids in cache with site-specfic keys.
Learner-1146

There are a number of Django Signals that are on the modulestore's
SignalHandler class, such as SignalHandler.course_published. These
signals can trigger very expensive processes to occur, such as course
overview or block structures generation. Most of the time, the test
author doesn't care about these side-effects.

This commit does a few things:

* Converts the signals on SignalHandler to be instances of a new
  SwitchedSignal class, that allows signal sending to be disabled.

* Creates a SignalIsolationMixin helper similar in spirit to the
  CacheIsolationMixin, and adds it to the ModuleStoreIsolationMixin
  (and thus to ModuleStoreTestCase and SharedModuleStoreTestCase).

* Converts our various tests to use this new mechanism. In some cases,
  this means adjusting query counts downwards because they no longer
  have to account for publishing listener actions.

Modulestore generated signals are now muted by default during test runs.
Calls to send() them will result in no-ops. You can choose to enable
specific signals for a given subclass of ModuleStoreTestCase or
SharedModuleStoreTestCase by specifying an ENABLED_SIGNALS class
attribute, like the following example:

    from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase

    class MyPublishTestCase(ModuleStoreTestCase):
        ENABLED_SIGNALS = ['course_published', 'pre_publish']

You should take great care when disabling signals outside of a
ModuleStoreTestCase or SharedModuleStoreTestCase, since they can leak
out into other tests. Be sure to always clean up, and never disable
signals outside of testing. Because signals are essentially process
globals, it can have a lot of unpleasant side-effects if we start
mucking around with them during live requests.

Overall, this change has cut the total test execution time for
edx-platform by a bit over a third, though we still spend a lot in
pre-test setup during our test builds.

[PERF-413]

This adds functions to the catalog utils which munge data
collected from the program endpoint and LMS database to construct
data structures that are ready for use by view and templates
related to the Open EdX marketing pages that live in LMS.

WL-766

WL-926

This commit contains back end changes necessary to load programs from the catalog in all contexts. The existing program munging utility is applied as late as possible to avoid conflating this work with changes to the front end; those will be made separately.

ECOM-4422

Added enterprise link, moved media kit down to second line, and adjusted styling
to avoid wrapping when possible.

2. Add site configuration overrides to theming/helpers.py
3. Move microsite.get_value from theming/helpers to site_configuration/helpers
4. Move microsite_configuration.microsite.get_value usages to site_configuration.helpers.values

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

* mattdrayer: Add helpers.get_value test
* mattdrayer: Change to simpler implementation, per @douglashall
* mattdrayer: Address quality violations and test failures

* mattdrayer: Add helpers.get_value test
* mattdrayer: Change to simpler implementation, per @douglashall
* mattdrayer: Address quality violations and test failures

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

Org to filter by is provided to the Course API list view using a querystring argument. Filtering ultimately occurs at the database layer. ECOM-2761.

Per Dave Ormsbee:
> That was from way back when, when we actually had Django server pools,
> proxied differently by nginx; one was the courseware, and the other
> was askbot, a discussion forum.
>
> They shared all the same code, but different parts were live. It was
> about as good an idea as it sounds.
>
> There is no reason that I can think of in the current day and age where
> you would ever want to run the LMS and *turn off courseware*.