title: FOSRestBundle: ExceptionController not triggered
body: <p>config.yml:</p>
  
  <pre><code>twig:
      debug:            %kernel.debug%
      strict_variables: %kernel.debug%
      exception_controller: 'FOS\RestBundle\Controller\ExceptionController::showAction'
  
  fos_rest:
      routing_loader:
          default_format: json
      view:
          view_response_listener: force
          force_redirects:
              html: true
      format_listener:
          rules:
              - { path: '^/api', fallback_format: json }
              - { path: '^/', fallback_format: html }
      param_fetcher_listener: force
      body_listener: true
      exception:
          codes:
              'Symfony\Component\Routing\Exception\ResourceNotFoundException': 404
              'Symfony\Component\HttpKernel\Exception\NotFoundHttpException': 404
              'Doctrine\ORM\OptimisticLockException': HTTP_CONFLICT
  </code></pre>
  
  <p>But html is returned:</p>
  
  <pre><code>...&lt;h2&gt;&lt;span&gt;2/2&lt;/span&gt; &lt;abbr title="Symfony\Component\HttpKernel\Exception\NotFoundHttpException"&gt;NotFoundHttpException&lt;/abbr&gt;: No route found for "GET /api/user/jFvms0rp%20"&lt;/h2&gt;...
  </code></pre>
  
  <p>How to turn it to json?</p>