Updates for Web API

Added new AlternateType HttpRoute for WebAPI routes
Added new Process Constraint Message type due to differences with MVC
routing
Modified RoutesInspector to work with Web API routing
Updated for WebAPI
Delete ProcessWebApiConstraintMessage.cs
Delete HttpRoute.cs
Fix for #365
Update Glimpse.AspNet.csproj
Update RoutesInspector.cs
Updated to allow RouteBase derived types
Merge pull request #723 from PaulAtkins/master

Can no longer access the list of Web API descriptors after installing Glimpse in our MVC4 project (#365)