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
Merge branch 'master' into virtual_units

Conflicts:
	modules/core/app/models/DocumentaryUnit.scala
	modules/core/app/views/Helpers.scala
Merge branch 'master' into virtual_units

Conflicts:
	modules/archdesc/app/views/documentaryUnit/show.scala.html
Update dubious compat server runner for Neo4j 1.9.7
Refactoring and cleanup of JSON parsing stuff.
 - make equalsReads and nullableListReads/Writes/Format a method on
   a JsPath extension class (looks neater and more consistent)
 - various formatting cleanups and reindentation
 - fix reading of virtual unit description references
More clean up of JSON reads
More JSON cleanup and refactoring
Add note to docs about  extensions