Fixes bug 968493 Scrape update_channel information into raw_update_channel for b2g
* Add new tables for update_channel
* Adds update_raw_update_channel() and backfill commands
* Make it possible to run the update_raw_update_channel() multiple times
* Add crontabber job
* Make rewrite rule a JSON type
Migration for bug 968493 add raw_update_channels and friends
Adds fakedata and corrects typo in models.py r=rhelmer
Merge pull request #1866 from selenamarie/bug968493-scrape-release-info

Bug968493 scrape release info