Week 5 - Checkpoint: Facebook Authorization
+ added gems 'Omniauth' and 'Omniauth-facebook'
+ updated User model attr_accessible so omniauth values are accessible
+ updated divise initializer to activate Omniauth functionality
+ updated application.yml with Facebook app keys for development and production environments
+ created application.example.yml for other developers
+ updated devise declaration in user model for omniauth compatibility
+ added redirect controller for devise to handle facebook authoriaztion redirect
+ added find for facebook authorization to user model.