Fix static links for footer images

Re-enable tests that were failing on Jenkins.

Use assertIsInstance where we can

Disable non-deterministic test to get stability on master

Remove unnecessary call from wordcloud test

Use wait_for to allow course image time to update

Valera/add option transcripts remove onhover

Don't remove course update when clicking outside modal.

Rework drag/drop on overview and subsection pages.

re-enable some buttons on instr dash

There were previous merge conflicts in the file.

When auto-show/auto-hide is disabled, the captions will be shown when
the user will move the mouse over the "CC" button. They will then
auto-hide after a while if the user doesn't continue to move the
mouse over the "CC" button, or over the captions themselves, or use
the keyboard to select a specific caption. If the mouse pointer is not
over the captions or the "CC" button, they will hide after a while.

This is the key in the fix for bug BLD-355: Transcript hovers over
over videoplayer itself for PKU videos.

Front-end functionality was not removed. When flag is set to "True", old
behaviour of autohiding of controls and captions will be enabled.

Use css_has_value() to fix failure in course-overview.feature

Also includes RequireJS changes.

Fixes bugs:
STUD-755, STUD-152, STUD-700, STUD-699

Add CSS classes and fix drop destination bug.