RoslynCompilationService should set the generated code when compilation is successful

Fixes #895
Enabling basic input formatter selection.

Conflicts:
	Mvc.sln
	src/Microsoft.AspNet.Mvc.Core/Formatters/TempInputFormatterProvider.cs
	src/Microsoft.AspNet.Mvc.Core/Microsoft.AspNet.Mvc.Core.kproj
	src/Microsoft.AspNet.Mvc.Core/ReflectedActionInvoker.cs
	src/Microsoft.AspNet.Mvc.Core/ReflectedActionInvokerProvider.cs
	src/Microsoft.AspNet.Mvc/MvcServices.cs
	test/Microsoft.AspNet.Mvc.Core.Test/Microsoft.AspNet.Mvc.Core.Test.kproj
	test/Microsoft.AspNet.Mvc.Core.Test/ReflectedActionInvokerTest.cs

Conflicts:
	src/Microsoft.AspNet.Mvc.Core/Formatters/TempInputFormatterProvider.cs
[Fixes #1035] RouteGroupConstraint should only be added once for non attribute routed actions

1. Changed ReflectedActionDescriptorProvider to add RouteGroupConstraint only once
   for non attribute routed actions.

2. Added tests to cover the scenario.