Addition of new event trigger in Illuminate\Routing\Router prior to response generation.

I've run into a few cases where it would be useful to hook into route dispatch process without using filters. The best example I can think of is a route-based menu system where the matched route is used to flag a particular menu item as being active *before* the response is generated. Such functionality IS possible using a 'before' filter but it's far from elegant and a blatent misuse of this feature.

This is why I'm proposing that a new event is fired immediately after the call to $this->findRoute($request) in Illuminate/Routing/Router. I've also included a test to ensure that the event is triggered with the expected response and route parameters though it could be a little over-complicated.

Hope this makes sense!