Actions :: Consolidate and cleanup Collections

 - Consolidate action collections into one actionDoc collection.
 - Add actionNotificationDoc collection to split notifications of newly
   enqueued Actions from notifications of changes to the Actions.
 - Add new StringsWatcher: actionStatusWatcher for watching actions that
   are in a specific state.
 - Move state Action specific code all into the action.go file.
 - Move interface definitions into interface.go.
 - Refactor ActionReceiver calls to keep db access all in the core
   action.go file.  Also use names.Tag in more places.

(Review request: http://reviews.vapour.ws/r/502/)