Add Facebook OmniAuthorization

* Add OmniAuth Gems

* Added User model and Sessions Controller for
  Facebook OmniAuth Login

* Formatted Navbar with OmniAuth Login

* Clean up Gemfile
Add themoviedb gem

* Added themoviedb gem and use it to provide
  movie data.

* Minimal UI/views creation to ensure the api
  connection works. Will further create UI in
  a separate story.