Beeminder Oauth controller

I created the sessions controller to handle the oauth from beeminder.  I
also added the routes so that it will actually authorize users.
Database issue with Postgresql

At this point, I'm not using a DB.  Rails was throwing an error because
it couldn't find my postgresql server in the devel environment so I
changed it to sqllite only for development.  When I start using a db,
I'll change it back.