AI-616 Updated ODK endpoints to use the ResourceLocatorAdaptor

The ResourceLocatorAdapter is an intermediate step on the road to the
ResourceStore interface originally envisaged for this component.

Also refactored the code for clarity, ensured that reference choice
sets are fetched only once.
AI-616 Refactored FormSubmissionResource for clarity
AI-616 Updated authentication to work with ResourceLocator / DispatcherSync

Other change: form id is now formClassId to ensure that ODK will smoothly process
updates for a given form. When the token is used as the form id, it looks like
a completely different form every time. The authentication token is now
stored as the userID.
Merge branch 'master' of github.com:bedatadriven/activityinfo