Specialist documents and CMA case refactor

* Move in SpecialistDocumentEdition from content_models.
* Extract view concerns into CmaCaseForm object
* Removed CMA specialisation from SpecialistDocumentEdition
* Created a CmaCase decorator.
* Removed CMA Importer.
In RSpec 3.0 there is a no monkey patching mode which I think we should move towards using. With this mode enabled the describe method is not added to object so the top level describe must be called on the RSpec module.