WIP backdrop migrations
Replace hyphens with underscores in bucket names

The job of allowing hyphens in bucket names has been moved to another story as there is more work to it.
Re-add fco realtime collections.
Make realtim fco bucket names match format of others
P to the E to the P to the 8... PEP8!
Use consistent naming for tokens
Merge pull request #103 from alphagov/add_capped_collections_for_realtime_data

Add capped collections for realtime data