Increment response listener priority in order to avoid New Relic transactions with false application name

This pull request is a bug fix. 

The priority of the request listener should be increased to be executed just after  the `Symfony\Component\HttpKernel\EventListener\RouterListener::onKernelRequest`, otherwise all the Symfony application request won't be assigned to the right application name in NewRelic.

In order to reproduce the problem, it is easier if you use the standard Symfony authentication system and call  the `logout` route of Symfony. You will see how the NewRelic transaction will not be asigned to you application name defined in the bundle configuration.