Use type classes more consistently for controller-model dependencies
Remove unused vars in controllers
Rename and move backend type classes
Clean up erroneous imports
Backend content types are always (also) resources. The type class now extends resource so we don't need both at the call site
Remove unnecessary client writeable params
Merge branch 'master' into virtual_collection_rework_merge

Conflicts:
	modules/core/app/backend/rest/RestGeneric.scala