Pull test dummy controllers into dummy rails apps

[phillbaker]

Dummy controllers/mailers probably belong in the dummy rails apps.

See:

• https://github.com/assaf/vanity/blob/master/test/experiment/ab_test.rb#L3
• https://github.com/assaf/vanity/blob/master/test/rails_test.rb#L3
• https://github.com/assaf/vanity/blob/master/test/rails_dashboard_test.rb#L3
• https://github.com/assaf/vanity/blob/master/test/rails_test.rb#L191