Refactor doc params filtering to abstract doc

Since this is going to be used in other document controller types, it
makes sense to refactor this out to asbtract_documents_controller.
Views, controllers and services for IDFs

This commit has a lot of stuff in it, but it's only adding controllers
and views for International Development Funds along with their
associated service registries (and for attachments too) along with a
view adapter.
Add permission check for DFID editors
Adding observers for IDFs
Move User cucumber step to access_control_steps
Testing International Development Fund workflow