The happy_seed:facebook depends upon happy_seed:omniauth and
If you want to have the user connect via facebook, this is the one line command for it.
FACEBOOK_APP_ID=
FACEBOOK_APP_SECRET=
In config/initializers/devise.rb make sure that the scope you are requesting is correct.
Since you need to set the callbacks as urls, you'll need to create one app for local development and another app for production. (Possibly one for staging as well.)