Add International Development Fund Model
Set up repository, builder and validator for IDF
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