LMS: FIX - Add Styling Back to Certificate Download Button

small bugfixes for theming+sass+templates

Individual Due Date Extension feature

Adds a feature to the edX platform which allows instructors to set
individual due dates for students on particular coursework. This code is
meant primarily for on-campus use--it is not intended that this feature
would be used for MOOCs. It adds a new tab, "Extensions", to the beta
instructor dashboard which allows changing due dates per student. This
feature is enabled by setting FEATURES['INDIVIDUAL_DUE_DATES'] = True.

Copyright Notice Updates

Sarina/remove university refs

change ruby and to &&

Revert "small bugfixes for theming+sass+templates"

This reverts commit 5f3313ec.

Disabled video updateplaytime JS test

Add apostrophe to lorem and fix single-quoted strings

* adds in Sass placeholder to mirror older/inherited button styling used in LMS
* uses light theming Sass variables for button styling
* adds specific selector for certificate download button

Sylvia/documentation/aa updates

small bugfix for theming+sass path

Disabled static pages and course team test seen to fail in master

Disabled video start and end time test

Add a command to transfer students from one course to another.

Fix bug about draft verticals reordering.

Video: Fix volume cookie.

STUD-714

Fix register button on edge

Not just students that are currently active.  Students may have enrolled with verified certs, paid, gotten
a refund, and un-enrolled from the original course.  This function should now capture that.

Enable pure XBlocks, hidden by feature flags

[LMS-226]
[LMS-2013]