add gem omniauth-facebook
add omniauth config
fix env variables in the omniauth.rb/
add sessions controller
 add , via: [:get, :post] to routes and run rails g model user provider uid name oauth_token oauth_expires_at:datetime
run rake db:migrate
add todo.md
add code to user model
add private method to application controller
finish the facebook oath tutorial and change gems to gem omniauth
gem omniauth-facebook, 1.4.0