Added API for oSUMO.

For more information, see https://github.com/mozilla/kitsune/pull/1444

It's all rebased and stuff! 

Should be fairly stable.

One thing:

 - If you run a test. You need to run `./manage.py cron build_kb_bundles`. Probably should get this resolved so that the code uses a different redis bin in test mode. (How?)