This change also starts passing in the manifest interface, rather than the raw data, to the model for writing.
Note that this change does *not* backfill the existing rows in to the new tables; that will occur in a followup PR. The new columns in `tagmanifest` and `tagmanifestlabel` will be used to track the backfill, as it will occur in a worker.
before we would return a 400 without a message because the errors were not being caught
Issue: https://www.pivotaltracker.com/story/show/145459707
- [ ] It works!
- [ ] Comments provide sufficient explanations for the next contributor
- [ ] Tests cover changes and corner cases
- [ ] Follows Quay syntax patterns and format
