Remove unused code when download from youtube.
Update the discussion area broken span tags
FOR-578
Merge pull request #4105 from edx/alex/remove_unused_code_when_downloading_from_youtube

Remove unused code when download from youtube.
updating diff-cover to 0.5.0
dummy theme templates for testing
tests for PR 3769

Two out of three fail without PR 3769 but all pass with PR 3769.
Merge pull request #3770 from mlkwaqas/waqas/for578-post-selection-broken-span

Update the discussion area broken span tags
Merge pull request #4201 from edx/jtauber/test-PR3769

Test PR 3769 (Improves the way LMS serves /favicon.ico)
Merge pull request #4219 from edx/clytwynec/diff-cover-update

updating diff-cover to 0.5.0
Increases wait_for_notification timeout to 60 seconds
Uses present in bokchoy test
Merge pull request #4223 from edx/benmcmorran/increase-notification-timeout

Increases wait_for_notification timeout to 60 seconds
Display names, help text, and "deprecated" for Advanced Settings.

STUD-302, STUD-303
Merge pull request #4073 from edx/christina/advanced-settings-hack

Display names, help text, and "deprecated" for Advanced Settings.
Enable Mixed Modulestore STUD-1540
Refactor get_parent_locations STUD-1663
Merge pull request #3915 from edx/studio/uses-mixed-modulestore

Enable mixed modulestore