title: getUser() returns null, session is not started in my symfony controller
body: <p>On the latest Symfony 2 version (using FOSUserBundle and SonataUserBundle), I am trying to get the current user in order to pre-fill a form in my new Entity controller.</p>
  
  <p>On <strong>mycontroller.yml</strong>:</p>
  
  <pre><code>my_controller_new:
      pattern:  /new
      defaults: { _controller: "MySiteBundle:MyController:new" }
  </code></pre>
  
  <p>On <strong>MyController.php</strong> :</p>
  
  <pre><code>public function newAction()
  {
    $user = $this-&gt;getUser();
    // ...
  }
  </code></pre>
  
  <p>But when I call <code>$this-&gt;getUser()</code>, the method returns <code>null</code>. Even though I am logged in (I can access <code>/profile</code> and update my user info without any problem)</p>
  
  <p>I then tried to check is the session was started:</p>
  
  <pre><code>public function newAction()
  {
    var_dump($this-&gt;get('session')-&gt;isStarted());
    // ...
  }
  </code></pre>
  
  <p>It returns false. What is wrong here?</p>