title: Symfony2 FormType bindRequest binds 000 as null
body: <p>Symfony2 forms bind 000 input as null, is this intended?</p>
  
  <pre><code>// FormType
      $builder
          -&gt;add('dummy', 'text');
  
      $builder-&gt;addEventListener(FormEvents::PRE_SUBMIT, function (FormEvent $event)
      {
          $data = $event-&gt;getData();
          dump($data); // This correctly dumps dummy as 00000
      }
  // Input 00000 in to the field and submit to controller
  
  // Controller
      $form = $this-&gt;createForm();
      $form-&gt;handleRequest($request);
  
      if ($form-&gt;isValid()) {
          dump($form-&gt;getData()) // dummy dumps as null, if i change the field type to integer, it dumps as 0, rather then 00000
      }
  </code></pre>