Reacting to System.Text.Encoding package version change
Allow MvcRazorHost to run on vanilla .NET45
- Added net45 target and removed specific aspnet50 and aspnetcore50 APIs
from that code path.
React to renaming TargetFramework to RuntimeFramework
[Fixes #739] Attribute Routing: Multiple routes per-action

1. Support multiple [Http*] attributes on an action.
2. Support multiple [Route] attributes on a controller.
3. Detect attribute routed actions during action discovery
   and return one action per [Http*] found on the method.
4. Build one action descriptor per [Route]+[Http*] combination
   in an action.
4. Disallow the use of [AcceptVerbs] and other IActionHttpMethodProvider
   attributes in attribute routed actions.
5. Disallow mixing attribute routed and non attribute routed actions on
   the same method.
Make AcceptVerbsAttribute IRouteTemplateProvider
Addressed feedback