Add OAuth, OmniAuth, and OmniAuth-Goodreads.
Add Link and Route for goodreads login.
Add Login with Goodreads OAuth functionality.
Change User migration to include provider, uid.
Add User model methods create_with_omniauth, random_username, random_password.
Merge pull request #92 from tiger-swallowtails-2014/gr_oauth

Goodreads OAuth functionality