New API Debug Mode. 

If enabled, any exceptions handled by Dingo Router will add an additional debug key filled with exception information.

This PR aims to solve the issue brought up by #69. There are somethings I am not sure about, such as the Config facade use, or the adding of HTTP Request information.

Up to discussing further to refine this. We could make this super basic, or even go as far as to write in custom formatting for the trace output. But don't want to overkill this.
It is not. I noticed that the Container class is already injected into the Illuminate\Router, and was going to use that to get the instance of `Config`. And it works, but the tests are failing since all classes are not being loaded and the container cannot `make` an instance of Config.

You're method totally works, but I'm trying to see if there is a way that doesnt involve overloading the constructor just for a single boolean value.