Move SpecialistDocumentEdition over from content models

Remove outdated extensions file.
Remove unused code from SpecialistDocumentEdition

Most of this was a hang over from original Edition?
CMA case form object
Remove CMA-specific fields from SpecialistDocument

This is done by extracting CMA case object.
Remove CMA import scripts
Pull in specialist_document_edition factory from content_models

Merge all factory definitions into a single FactoryGirl.define block.
Remove CMA-specific params from manual document builder
Merge pull request #108 from alphagov/refactor-cma-cases

Specialist documents and CMA case refactor