title: getting Facebook ID of an already registered android Account
body: <p>I want to get the facebook ID of an Android Account. If it's possible, would like to use the Facebook SDK to do some things like posting on the wall.</p>
  
  <p>How can i get the informations from the AndroidAccounts ?</p>
  
  <p>Currently i can get my Gmail address with the accoutManager.</p>
  
  <p>Thanks</p>