title: Migrating old facebook authentication keys to access_token
body: <p>I am working on an old application, which is now going to be updated so we can support the new Facebook features. I noticed that the user model have uuid, atoken and asecret facebook keys.</p>
  
  <p>In the old site users had the ability of login in with Facebook and posting status updates. The thing is that I need to migrate the old user information to the new schema.</p>
  
  <p>My wonder is, since I do not have an access_token for my users, how could I convert the token and secret Facebook keys to an oauth2 access_token, since I need the old users be able of using the application almost without noticing any architectural changes just the ones in design.</p>