Use RSS feed data to fill in title/description (#731)
Get Kaltura IDs from Video URLs (#731)

Refactored the VideoUrl class a bit to make it easier to get the video
type from it.  Added an extra_info() method to VideoUrl and VideoType
so that we can get type-specific info.  Made a KalturaVideoType class.
Different way of getting the kaltura id.

The extra_info() method wasn't a good idea because some video types
(Youtube) require a bunch of work to be instatiated.  Made a specific
method for this so that we don't have to worry about that.
Fix for Video.get_video_url()
Made entry parsing work on the initial import

We have 2 ways to import videos into from a feed: the
tasks.import_videos_from_feeds() method and VideoFeed.update().  Both
of them basically did the same thing, but with duplicate code.  I only
updated the VideoFeed.update() method, so the initial import wasn't
picking up the titles.

Refactored things so that the importer code is in
feed_parser.VideoImporter.

Refactored the video feed tests and added a teams feed test.
Fixed exception after we finished the import task
Add support for iTunes RSS extensions (#732)
Merge pull request #840 from pculture/gh-731

Gh 731