Removing crufty old code from the codebase.
Cleanup to the UI interface (which was no longer used).

* Pull in play-json for now, for serialization.
* Remove stale UI interface code.
* Pull in new UI interface proposal.
Migrate to sbt 0.13 and the play json API.

* Remove RawStructure in its entirety.
* Migrate complex Formats to Play's JSON API.
* update the mechanism we use to serialize/deserialize events.
* Upgrade to sbt 0.13
* Minor cleanups.