private function buildKernel(Request $request, RouteCollection $collection)
 {
     $kernel = new AppKernel('dev');
     $kernel->listen($request);
     $kernel->addListenerOnce(KernelEvents::BOOTED, array($this, 'onBooted'), 10);
     $kernel->addListenerOnce(KernelEvents::REQUEST, array(new RouterListener($collection), 'onRequest'));
     return $kernel;
 }