only the sources (not the player)

-- Changed docstrings to use double quote.
-- More consistent naming for youtube IDs (normal_speed_id -> youtube_id_1_0).
-- Formatting changes for readability.
-- Updated test XML to expect JSON-encoded strings; prevents tests from spuriously failing.

TODO: This breaks the 1.5x and .75x speeds. I'm still looking into
why.

TODO: VideoDescriptor inherits from RawDescriptor in order to
use the from_xml and export_to_xml methods. This seems really ugly,
though; I'd rather find a better way to do this.

Use MITX_FEATURES to tell if we're in the CMS; this is much cleaner. Also use $.data instead of a hidden div.

Conflicts:
	lms/templates/video.html

wire through course asset path information to the video playback module and corresponding .coffee files

Add a download link to the video player. The link is defined
in the content xml using the following structure:

<video youtube="youtubestring">
    <track kind="subtitle" src="subtitle_link" />
</video>

Add a download link to the video player. The link is defined in the
content xml using the following structure:

<video youtube="youtubestring">
  <source src="video_link"/>
</video>

* update templates and code references
* also a display_name property that defaults to cleaned url_name

Get the video module pointing to the correct static files directory, without relying on get_html replacement

Make user profiles work again after the switch to an XMLModuleStore. Staff user histograms are still broken