title: required field not working on internet explorer 9 with symfony form
body: <p>i've created a form with symfony 2, but my browser internet explorer 9 (running under vista)  doesn't support HTML5. so i get this error message:
       an exception occurs: SQLSTATE[23000]: Integrity constraint violation: 1048 Column     'name' cannot be null.</p>
  
  <p>i've tried this solution:</p>
  
  <pre><code>{# src/Acme/DemoBundle/Resources/views/Default/new.html.twig #}
  
  {{ form(form, {'attr': {'novalidate': 'novalidate'}}) }}
  </code></pre>
  
  <p>but it doesn't change anything!</p>
  
  <p>the submit of the form perfectly works on firefox. does anyone have a real detailled solution for IE9?</p>
  
  <p>Thanks</p>