title: Handle Twitter / Facebook Authentication in App
body: <p>I want users of my app to be able to authenticate with Twitter and Facebook. This way I know they are a real user. Once they've authenticated once I don't want to have to worry about them logging out or re-authenticating unless they explicitly do so.</p>
  
  <p>I'm storing/displaying the users avatar image. How might I handle if the user were to update this on their given platform? My stored image URL will now be out of date correct? User would essentially have to logoff and re-authenticate in order to have their data updated which isn't ideal...</p>