title: Symfony2 dev environment not clearing cache automatically
body: <p>I'm working on a new Symfony2 project, and I'm using the app_dev frontcontroller to view the default AcmeDemoBundle's pages. </p>
  
  <p>When I make changes to the controllers, I get an exception (<code>NotFoundHttpException: No route found for "GET /demo/hello/World"</code>). If I clear the cache using <code>php app/console cache:clear</code>, things work great again. However, it is my understanding that by using the app_dev front controller, I shouldn't be required to do this. Am I doing something wrong?</p>
  
  <p>Soms system specs:
  OSX Lion using MAMP
  PHP 5.3.6
  Symfony 2.0.1</p>