Converts the dates on the dashboard, sidebar navigation, and important course dates to user specified time zone.

REST APIs modified

CCX overrides course max_student_enrollments_allowed
and set it to 200 during CCX creation

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

Also remove useless docstrings where they were added to keep pylint
quiet.

This reverts commit 42e78463.

This reverts commit 53db053c, reversing
changes made to 386a8a27.

This reverts commit d80e8364, reversing
changes made to fb5506a6.

enrollments.

The goal for this PR is to have a single mechanism for registering users and
reducing the number of places where special-casing for ccx courses is needed. The
migration at this point is purposefully limited to convert ccx memberships into
student enrollments when moving forward. No backward migration is in place at the
moment. The ccx membership tables are not removed at this time. It is possible to go
backwards and forwards multiple times with no errors or data loss.

Use the lazy module to create cached attributes

Ensure tests for localized date formatting are insulated from changes in default formatting

Other minor fixes

refs https://openedx.atlassian.net/browse/TNL-2009

repairs https://openedx.atlassian.net/browse/TNL-2007 and https://openedx.atlassian.net/browse/TNL-2009

Original Commit Messages:

Update ccx dashboard display to match new course display

Fix display of CCX dates on dashboard to use dates from the CCX instead of the related course.

The fix is implemented by providing date- and course-related APIs on the CCX object itself.  These APIs are mimicked from the same APIs available on a course descriptor.

bring the methods for printing start and end datetimes into line with course by adding UTC under the proper circumstances

add test coverage for new APIs defined on the CCX model

fix quality violation

add doc strings; fix pep8 warning
address some minor issues brought up by the code review process

Final official name is Custom Courses for EdX (CCX), rename all code to remove previous name.

Rename the FEATURE constant used to identify this feature

Rename the middleware for the CCX change

rename the constant used for storing the current poc id on the session.

rename the _PocContext threading local

rename the override provider in all places where it is referenced

`PersonalOnlineCoursesOverrideProvider` -> `CustomCoursesForEdxOverrideProvider`

generally rename symbols from overrides.py to replace `poc` with `ccx` where possible without changing model names or attributes

rename more symbols from poc to ccx
rename util functions from app utils module

general symbol renaming poc -> ccx in views.py and related url changes

Rename the coach role wherever it is used.

reword poc_coach to ccx_coach

UI rename

replace POC with CCX globally

template context variable renamed

rename poc_ to ccx_ in urls and all related locations (views, js, scss etc)

remove pocs migrations

Final massive renaming, including models.  Re-built migration.

cleaning up a few tailing references

Fix reference typo in schedule template JS

undo modifications made on the fly in test setup to ensure that our tests are properly isolated from the rest of the system tests.

Fixes jazkarta/edx-platform#38

Clean up some leftover strings and comments

fixing more strings and comments in python files

fix a naming error in the schedule tab that was causing problems in deleting courseware items.

Fixes jazkarta/edx-platform#36

updating tests and utility code to match changes in infrastructure from latest rebase

Show the display name for the POC in the menu for switching.

Remove the MOOC: prefix from the MOOC title to avoid truncation issues.

Incorporate the display name of the POC into the display of course org/number/name at the top of the page in the default theme.

Provide warning on the grading policy page in system warning style.

Provide a PocMembership model api that returns PocMemberships for a user.  Default to active memberships.

Build generator that yields triplets of poc, membership and course for each poc membership a user has.

This is an analog of the `get_course_enrollment_pairs` in common/djangoapps/students/views.py and is used in the student dashboard to provide pocs as options for a student to view.

refactor to use model api instead of inline code.

provide pocs as possible targets for a student to visit from their dashboard.

Unset the current active poc when visiting the dashboard so as to avoid needing to switch active pocs when viewing a plain course.  This ensures we can leave template code for the display of courses unchanged.

Update templates to show pocs in a course-like view on a student's dashboard.

Revert a portion of the template change so that the poc title will still render properly when a poc is being viewed.

Remove over-cautious assertion and allow calling errors to be calling errors

fix problems in auto_enroll method

ensure that the active poc is wiped out if the user has no poc membership

Based loosely on course enrollment model

Ensure that registered users are 'active' when they are enrolled in a POC

Respect the 'auto enroll' and 'email students' checkboxes in the UI

Add an auto_enroll flag to the PocFutureMembership model so we can automatically enroll non-users when they have registered and activated their account.

Build a future enrollment using the auto_enroll value from the request so we can ensure that non-existent users can be auto-enrolled

Ensure that any user added by way of the one-at-a-time UI is automatically auto-enrolled

Update tests with email sending to use the flag from the request

Provide api on the PocMembership object to auto-enroll a newly active member in this poc.

This method will delete the passed PocFutureMembership object and will automatically enroll the user in the POC named in that future membership as well as the MOOC from which it was created

Conditionally activate poc memberships that are pending when a new registree first activates their account.

This feature provides the ability to designate a "coach" who can create customized runs of an existing course, invite students to participate, and manage students through the run of the course.

In this squashed commit we implement the initial scifi, add the 'POC Coach' course role, refine the scifi, add migrations for models, create POCs, enforce POC Coach role, provide panels for Coach Dashboard, set up rudimentary display of course outline, add and remove units, show/hide all units, and save schedule changes, set dates when adding units, edit dates on units already added and provide some tests.

We also provide mechanisms for invitation and enrollment in a POC (to become CCX) and control the display of blocks to students in a POC.