fix(controller): Determine registry address during start

**DO NOT MERGE** Before this change re-deploying apps failed when the registry was re-scheduled to a different instance in the cluster.

Fixes #1128

- [ ] Store just the image name and tag in the build model
- [ ] Prefix the image reference before fleet pulls the image
- [ ] Prefix the image reference before controller pushes config changes to the registry
There's no need to refactor the whole PR as you mentioned in https://github.com/deis/deis/pull/1325#issuecomment-49465717. You can just remove the builder changes and just change this script to massage $1 for the app name. That should be completely backwards compatible, no?