title: Register with Facebook sometimes doesn't provide email
body: <p>I'm using Register with Facebook as one of the ways to log in to my web app, and expressly ask for the "email" permission..</p>
  
  <p>On login, some of the user data (<code>$facebook-&gt;api('/me')</code>) is stored into the users database, however, sometimes the email field just doesn't exist - is this a common problem?</p>