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.
Fixes per review feedback
Fix for feedback from review
More review feedback
Couple more naming suggestions
Merge pull request #1192 from johnweldon/2-action-refactor

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/)