Migrate video tests to videoalpha tests, remove video tests.
Remove js unit tests.
Make js unit tests out of Alpha.
Make VideoAlpha out of Alpha.
Python: videoalpha -> video.
Migrate acceptance tests: old Video -> new Video.
Disable js unit tests.
Working on Videoalpha test fix.

Fixed all common and LMS tests.

The tests were failing because XMLDescriptor adds in some attributes
to _model_data, such as `xml_attributes`, that aren't necessary. The
solution is to handle all XML parsing in VideoDescriptor. There's
still one test failing in CMS, which has to do with metadata being
saved. I'm still working out how to update it in such a way that it
doesn't fail, but still tests something meaningful.
Add acceptance tests for checking rendering.
Merge pull request #637 from edx/vaxxxa/videoalpha_to_video

Migration videoalpha module to one main video module