Recording events silexphp/Silex-WebProfiler#40

Removes a circular dependency (profiler > dispatcher > profiler) and provides dispatcher to ```EventDataCollector```. The latter enables recording of events in WebProfiler.

As per ```TraceableEventDispatcher``` documentation ```setProfiler``` method has been deprecated since version 2.4, to be removed in 3.0 ( symfony/http-kernel package ). Removing line 54 is *safe* except for installations having http-kernel 2.3