Fix/smaller images

Depends on WAD, because I wanted these tests to go pretty quickly.

Uses medium versions of images for the enclosures (may want a way to get other versions at some point in the future, but for now medium is appropriate for its use in thumbnails on 1-3x density displays)

Upgrades factory_girl_rails to avoid some really bizarre and confusing error messages (`ActiveRecord::AssociationTypeMismatch: Account(#70361709696620) expected, got GroupAccount(#70361656161660)`) which I believe I have surmised is caused by FactoryGirl holding references to the old definitions of classes after spring has reloaded them. The new version of factory-girl-rails forces factory girl to reload its definitions whenever spring changes anything.

Also adds a guard condition to re-run the suite whenever a factory is changed. Lots of things are dependent on them.