Fix Firefox subsection datetime bug

Fix videoalpha import from xml

Add "Word Cloud" acceptance tests

VideoAlphaDescriptor inherits from EmptyDataRawDescriptor.
EmptyDataRawDescriptor is used for modules which might not have any
XML data, but require XmlDescriptor's functionality for
export/import. Without it, VideoAlphaModule would cause a crash on
export if any modules had an empty `self.data` field.

Don't use default video if HTML5 sources are given.

Clicking "Sync to <course>" should send an AJAX request with the datetimes
set to null, so that the server resets them.

Assign isExternal JS function to window object

Fix offline_gradecalc

When JS functions are defined with names, they are local variables, and inaccessible
if defined inside a closure. Django-Pipeline concatenates all of our JS into one
big closure. This function explicitly assings the function to a property of the
`window` object, so that it is accessible to other JS functions.

Auto-enroll course staff to fix "View Live".

tz fix in openendedchild

Integrate JsonResponse into lms/djangoapps/instructor/views/api.py

template fixes on instructor dash

Bump up pip requirement to latest.

Peter fogg/remove videoalpha xml

tie in the normal courseware link url rewriting in capa module since tha...

Small fixup to final print statement in Create Dev Env script

Feature/cdodge/display location information in course listings

This is to be used with VideoAlpha's functionality allowing a choice
of multiple HTML5 video sources.

Firefox wasn't saving section release times, due to issues with JS Date() parsing.
I've modified the code to make it more explicit around what it should do and how
it should work, which also makes it work better with both Firefox and Chrome.

Fixed Typo

Performance enhancements for django-admin commands to delete and clone course

Remove _

Minor cleanup.

Add RawDescriptor for VideoAlpha