Add omniauth failure route
Use environment variable for facebook app id
Revert to omniauth-rails 1.4.0 since CSRF issues
Make omniauth callback path available via post AND GET
Revert "Revert to omniauth-rails 1.4.0 since CSRF issues"

This reverts commit c69789f59428c6fd7f283948b93c8f3b22683c83.