Subtitles immediate fix

Hey Dylan,

I figured out the issues we hit yesterday.  Basically, only the central server-side code (essentially, the two management commands) was to be merged; everything else was dangerous crap :)

I isolated those changes, merged them with develop, and tested them (showing some bugs and a few further changes).  All are done; you can cleanly merge this for your pull request.  If you want to view "true" changes before merging, you'll need to merge with upstream/develop first (and resolve merge conflicts).

To test, simply run the two management commands: `generate_subtitle_map` and `cache_subtitles`.  `generate_subtitle_map` will return quickly, as the slow results have already been run and checked in.

Once you merge in these changes, please open a new pull request against release-0.10.

Let me know if you have any questions or concerns!