Allow courses to set Matlab API key globally, in advanced settings.
Updated payload for new matlab endpoint.
Don't hardcode https protocol in enrollment emails.

Use http or https, depending on the value of `request.is_secure()`.
That is how links in most other emails are handled.
No longer chunk queries when sending out bulk email (LMS-2718)

refactor _generate_items_for_subtask not to chunk queries

use django's iterator methor for querysets

remove bulk email query settings

use read_replica if available, since this is read-only

update changelog
Add EASE to edx-platform requirements
Check YouTube Availabitlity for Video Tests
Annotation Tools: Load Tinymce in student_view
Annotation Tools: Fixing tests for student_view

Fixed typo from autocomplete

Fixed dict for tests
Updated version of event-tracking library to 0.1.0
corrected a typo; tried to clarify a different sentence
Merge pull request #3882 from edx/ammar/test-youtube-availibility

Check YouTube Availability for Video Tests
Merge pull request #3927 from edx/ahodges/documentation/DOC438

corrected a typo; tried to clarify a different sentence
Update help for welcome, register, and login pages

All now go to getting started, but have different tokens, for further
segmenting later.
Welcome page text edits
Merge pull request #3896 from edx/will/install-ease-and-requirements

Install EASE and requirements
Merge pull request #3841 from edx/fix/large-email-queries-2

Fix/large email queries 2
Move to OpaqueKey implementations from the external library

[LMS-2757]
Fix the title of edit modals from the unit page.
show a friendly message for an empty course rather than an error page
Fix location.url [LMS-2786]