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.

* 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)

This reverts commit 4c1c4619.

Fields are start_type, start_display, and courseware_access.

Fix n-click behaviour on poster.
Fix unit tests.
Fix handler for non_en lang for bumper.
Add more tests.
Fix docstrings.
Fix pep8.
Fix static redirection with bumper.
Fix button in IE11.
Add video_bumper field in bok_choy.

Fix pylink violations.

Update docstrings and some clean up.

Rename edx_video_id in bumper tests.

Fix too long lines in help text.

Address ui comments.

Fix bumper events.

Refactor bumper-transcripts code, fix bugs, address comments.
Squashed commits:
Fix download transcript button.
[74e0c8c] Fix quality
[a759f33] Fix error, when sub contains extension.
[b30755c] Revert "Add video files to host for transcripts."

This reverts commit cf8a96bf84346e17b6ad57ad4cc6a27d7a9118cd.
[36f038a] Add video files to host for transcripts.
[23f1655] Fix pep8 and pyling issues.
[0f1f9d2] Update acceptance test.
[765a27d] Wait for ajax in captions.
[8ae72a3] Fix logic.
[063450f] Fix unit tests.
[d1075fc] Fix handlers tests.
[25d31ad] Update bumper_utils.
[cb5f9df] Remove maxDiff.
[8738b1a] Code cleanup.
[87dbcb7] Fix issues with transcripts.
[ec899de] Fix transcripts in serializers.
[444b1fc] Fix transcripts typo.
[d524cb5] Fix bumper.
[f62cf22] Fix video mongo tests.
[8f1b55a] Fix dispatches.
[53bc308] Add more fixes.
[d5e3723] Fix test_video_handlers and rename the method.
[93efc23] Fix mobile tests.
[740e2ae] Fix pep8 and pylint.
[47cfb66] Address comments, add fixes.
[4e499d9] Add fixes.
[8353553] Add improvements.

Updated dispatch values)
.

Use ddt in bumper handler tests.

Move common metadata to single place.

Fix style.

Update docstring.

Fix poster button.

Improve bumper events.

Fix test after rebase.

Address comments.

Download transcript: use def video lang, not bump.

Renamed date_last_view_bumper to bumper_last_view_date.

Rename do_not_show_again_bumper to bumper_...

Address comments.

Fix tests for download for en lang.

Fix bumper logic.

Update strings.

Update resizer.

Remove resizer.

Fix unit tests.

Add tests.

Fix bumper events.

Clean up tests.

Fix pylint violations.

Fix pep8 and pylint violations.

Update docs and method names.

Update events.

Make /static/ prefix a must.

Fix wrong code.

Previously, the mobile api did not check for pre-requisite courses
or entrance exams. This change checks for these milestones and then
returns course content accordingly.

Update Mobile API to include channel_id for course.

TNL-1537

Co-Authored-By: Andy Armstrong <andya@edx.org>
Co-Authored-By: cahrens <christina@edx.org>

This is required so that an a video module exported by one Open edX
deployment and imported by another will work correctly if it contains an
edx_video_id but does not populate other URL fields.

JIRA: MA-110

MA-77 Automatically adds the course id to the videos in VAL
when a course is rerun.

MA-169 Mobile api now calls for mobile_low (default), mobile_high,
 and youtube profiles instead of only mobile_low.

This is needed for courses that license video content where the license
allows only for viewing on the web, not on mobile apps.

JIRA: MA-307