title: Disable deprecated warning in Symfony 2(.7)
body: <p>Since my <code>Symfony 2</code> update to <code>2.7</code>. I get a lot of deprecated erors in <code>PHPUnit</code> and <code>console</code> (message is clear by now). </p>
  
  <pre><code>ProjectX\ApiBundle\Tests\Controller\SectionsControllerTest::testPostDebug()
  The twig.form.resources configuration key is deprecated since version 2.6 and will be removed in 3.0. Use the twig.form_themes configuration key instead.
  </code></pre>
  
  <p>Any idea how to disable them for now? </p>