First pass master schema change for assets

Integrates asset, file, and container_asset tables into one.  Changes assets to attach to slots rather than containers.
WIP slot_asset unification

incomplete, inconsistent schema
WIP asset unification, now compiling

inconsistent schema
Muck with SlotAsset permissions and fuzzyDate
Minor query and schema fixes
Half way to synchronized schema
Synchronized, tested schema
Merge remote-tracking branch 'github/master' into asset

Conflicts:
	app/views/asset/edit.scala.html
Minor fixes for thumbnail extraction