Simplified resolving metric names in OWIN library

I've changed routes in the sample OWIN project to use http://superscribe.org. This allows route declarations to be web framework agnostic and resolved via the OWIN environment dictionary. 

Currently there is a dependency on OWIN environment keys provided by superscribe which could be made configurable. These keys are:

var parameters = environment["route.Parameters"] as IDictionary<string, object>;
var controllerName = environment["superscribe.webapi.controllername"] as string;