title: Github OAuth Provider - Get username or id
body: <p>I'm using the Firebase Authentication services to authenticate users using Github as the provider. The OAuth response returns the access-token for the user along with some other information (e.g. email, name...). For persistence-purposes I need to save the authenticated users <strong>username</strong> or <strong>id</strong>, but I can't seem to find that information in the OAuth callback. </p>
  
  <p>Am I missing something or is the user data just not provided using OAuth?</p>