title: Properly log out a user from android app
body: <p>I'm developing a small android app, and basically so far it just has login and logout functionality. I'm using Firebase to store user data and also for authentication. </p>
  
  <p>So I have login working and it authenticates users as it should and I have logging out working in the sense that it <code>unauthenticates</code> users. But is there anything I have to do from within the app to kill the session? </p>
  
  <pre><code>if (id == R.id.action_log_out) {
      ref.unauth(); //End user session
      startActivity(new Intent(MainActivity.this, LoginActivity.class)); //Go back to home page
      finish();
  }        
  </code></pre>
  
  <p>Will this work as I think it should?  Obviously if someone logs out they shouldn't be able to hit th back button and magically go back to the last page without re-logging in. </p>