Omniauth facebook without devise

- Added omniauth and omniauth-facebook gem
- created config/initializers/omniauth.rb
- Created signuper app on facebook developer platform
- Added "http://localhost:3000" to signuper facebook app platform
- Inserted facebook JavascriptSDK into index page
- input facebook APP_ID and APP_SECRET in .env file
- .gitignore .env file
- using /auth/facebook to request authentiation
- using /auth/facebook/callback to callback to signuper
Oh, I see, this is where you create your users — just saw that in your original comment.  This is fine, here, but I'd create a method like `User.create_or_find_with_omniauth(auth)` and then have this `||` logic in the model.