title: How to handle OmniAuth callbacks in multiple environments?
body: <p>I have an app that uses Facebook exclusively as a provider for authentication and have correctly setup the callback for production mode. In order for this to work, you provide your Facebook app with a site URL and a site domain for callbacks, and in my case it's <code>http://appname.heroku.com</code> and <code>appname.heroku.com</code> respectively.</p>
  
  <p>The problem is that my controllers are setup to only allow authenticated sessions so I cannot view my app in development mode because the Facebook app's domain obviously hasn't been set to localhost.</p>
  
  <p>How do I get around this without having to change it in Facebook's settings?</p>