Allow CMA Cases to have minor updates

Allow a minor update flag to be set on CMA case
in order to stop email alerts being sent when a document
is flagged as minor.
Allow Drug Safety Updates to have minor updates
Allow MAIB reports to have minor updates
Allow Medical Safety Alerts to have minor updates
Allow RAIB reports to have minor updates
Allow AAIB reports to have minor updates
Allow Int Development Funds to have minor updates
Merge pull request #319 from alphagov/feature/minor-updates

Minor updates for SpecialistDocuments