Fix a bug in Individual Due Date Extensions (IDDE).

The IDDE implementation relied on a StudentModule being created for a
particular block in order to set the extended due date on that block.
Since StudentModules seem to be created on demand whenever data is
written to an attribute with Scope.user_state, it meant that if a
homework problem hadn't yet been touched by a student it was possible
that the due date extension wouldn't take effect for that problem, even
if the due date extension was successfully set for the parent unit.

This patch fixes this problem by creating new StudentModules as
necessary in order to make sure extended due dates propogate properly to
all problems in a unit.
BLD-1190: Fix bok-choy test.
Remove LocMapperStore
LMS-2918
sql migrations cannot use loc mapper
Hotfix course_specific_reg/login for OpaqueKeys
Merge pull request #4413 from edx/remove-loc-mapper

Remove LocMapperStore
Remove warning filter from library code (should be set by applications/tests directly)
Merge pull request #3718 from jazkarta/idde-bugfix

Fix a bug in Individual Due Date Extensions (IDDE).
Tweaks for i18n docs
Fix quotation mark & apostrophe related i18n bug

Just done by using the escapejs function :)
Merge pull request #4449 from edx/ned/tweaks-for-i18n-docs

Tweaks for i18n docs
Merge pull request #4244 from Stanford-Online/jbau/edx/course-specific-login-opaquekeys

course_specific_reg/login for OpaqueKeys
Merge pull request #4447 from cpennington/squelch-deprecation-warnings-in-test

Remove warning filter from library code (should be set by applications/tests directly)
Merge pull request #4347 from louyihua/studio-advanced-settings-localization

Fix quotation mark & apostrophe related i18n bug
Merge pull request #4441 from edx/anton/fix-flaky--bok-choy-test

Video: fix flaky bok-choy test.
Make TinyMCE editor translatable

Combine TinyMCE's built-in translation scheme with the django's translation framework.
So edX's translators can also make translations for TinyMCE used in edX.
Merge pull request #4349 from louyihua/localization-cms

Make TinyMCE editor translatable
Add tests of cross-modulestore import/export

[LMS-2945]
Skip DraftVersioningModuleStore tests
Add the manual testing course for testing xml import/export across modulestores