more concise app and permission test definitions

This app's tests commonly need to create applications with certain
supported permissions, and users with certain permissions.

This change adds logic to the FactoryGirl factories to allow more
compact definitions of the common cases. A bump in the FactoryGirl gem
is needed to pick up the necessary syntax.
Merge pull request #139 from alphagov/more-concise-app-and-permission-test-definitions

more concise app and permission test definitions