Change answer <-> response matching in capa.get_submission_metadata
Add promise to ensure unit visibility is changed
New chapter on discussion features for all users
Check to make sure that the mysql service is running.
Create the test database if it doesn't exist.

There is a bootstrapping case where the test DB doesn't exist which causes reset_db to fail.
Merge pull request #4372 from edx/ahodges/documentation/discussionoverview

New chapter on discussion features for all users
Make text on register button on About page conditional.

 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.
Merge pull request #4418 from Stanford-Online/dcadams/make_registration_button_conditional

Make text on register button on About page conditional.
Merge pull request #4417 from edx/jbau/event-responsetype

Change answer <-> response matching in capa.get_submission_metadata
Disable test that is leaving modal open.

STUD-1963
Merge pull request #4430 from edx/feanil/fix_bokchoy

Feanil/fix bokchoy
Merge pull request #4435 from edx/christina/stud-1963

Disable test that is leaving modal open.
Merge pull request #4422 from edx/ammar/fix-handout-tests

Add promise to ensure unit visibility is changed
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.