handling all request execution with events. Closes #247

With this change, all infrastructure interceptors are now observing CDI events.

`ParametersInstantiator` observes `StackStarting`, `ExecuteMethod` observes 
`EndOfInterceptorStack` and `ForwardToDefaultView` observes `MethodExecuted`

Very soon I'll add a simple diagram explaining VRaptor events. This PR closes #247.