Add tests for xml import/export between different modulestores

Use field scopes to compute which metadata to strip from the definition during XML import of XMLModule subclasses

[LMS-2945]

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.

Video: fix flaky bok-choy test.

Fix quotation mark & apostrophe related i18n bug

Remove warning filter from library code (should be set by applications/tests directly)

course_specific_reg/login for OpaqueKeys

Tweaks for i18n docs

Just done by using the escapejs function :)

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

Remove LocMapperStore

LMS-2918

Add promise to ensure unit visibility is changed

Disable test that is leaving modal open.

Feanil/fix bokchoy

STUD-1963

Change answer <-> response matching in capa.get_submission_metadata

Make text on register button on About page conditional.

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.

 Added a new advanced setting; invitation_only

 If invitation_only display "Enrollment in this course is by invitation only"
 Otherwise, if outside of enrollment period display "Enrollment is Closed"

 This issue is logged at LMS-2670

 Also fixed in this PR is issue LMS-2717; even though the Register button was greyed out,
 clicking it sent one to the registration page.

New chapter on discussion features for all users

There is a bootstrapping case where the test DB doesn't exist which causes reset_db to fail.

Fix calls to get_module to not pass course ids as positions

Fix pending name changes template

Add JQuery timepicker CSS to the unit and container templates