Issue aspnet/Mvc#56 - merging RouteContext and RequestContext

This is the routing part of these changes, and just the breaking changes
parts.

Follow-ups will add:
- DataTokens
- Tracking the logical stack of routers
Changing to list
Routing DI Changes II : Adding services for routing.
Removing registration of Options.Services and renaming RouterServices to RoutingServices.
Responding to comments