title: twig filter from date to string
body: <p>Using Symfony 2.3.4 and Twig.
  I'm trying to show an objects attribute which is, and I quote, "an Object of Class DateTime" and I need something to convert it to a string(I'm guessing a filter).</p>
  
  <pre><code>{{ r.birthday }}
  </code></pre>
  
  <p>Any tips appreciated.</p>