DRY up minister and policy minister selection

Fixes https://www.pivotaltracker.com/story/show/81759396

* Removed brakeman from Rake (will configure it to run in travis)
* Moved controller helper methods as only used by view and simplified (using DB query)
* Moved minister/policy minister autocompletes into a partial
* Added RSpec config to automatically set the example group from the folder (needed for helper specs)