add omniauth-facebook to gemfile
migration for add provider and uid to users
declare facebook provider for omniauth
make user model omniauthable for facebook
add sign in with facebook link to application layout
add route for implementing omniauth callback
create controller for omniauth callbacks
facebook callback for omniauthcallbacks controller
method to find or create user from omniauth
method to copy facebook email if possible
route for logout with facebook
users route cleaned up to include facebook omniauth
test for sign in with facebook
trait for user with facebook account
factory for user accounts
factory for user_accounts fix
trait with facebook account for user add after create block
implement testing facebook login later