Initial work on virtual collection creation.

 - currently based on doc unit views
 - no i18n messages yet
 - doesn't allow actually linking descriptions yet
More copy-pasta allowing VUs to create virtual descriptions
Move VU controller/views to archdesc module, add search
Experimenting with logging
Tweaks to language rendering
Various small issues with virtual units
Merge branch 'virtual_units' of github.com:mikesname/docview into virtual_units
Fixes for selecting correct descriptions from 2-to-3 letter lang codes
Merge branch 'master' into virtual_units

Conflicts:
	modules/core/app/models/DocumentaryUnit.scala
	modules/core/app/views/Helpers.scala
Rename 'New Node' to 'Add Note' (fixes #216)
Make watch button visible
Refactor socially-related routes into their own controller
Refactor annotation-related actions into their own controller/spec
Add support for blocking/unblocking users to the social DAO
Initial scaffolding for user messaging
Remove maintenance notes from portal repo display
Merge branch 'master' into user_messages
More work on user messaging
More work on user messaging.
 - Added flag to account to allow disabling messaging
 - Allow updating account prefs from edit profile page
 - Rationalised logic for determining if a user can be messaged
 - Added tests
A few more tweaks and fixes to messaging