Temporarily disable MVC functional tests on net461

Author: rynowak

test/Microsoft.AspNetCore.Mvc.FunctionalTests/Microsoft.AspNetCore.Mvc.FunctionalTests.csproj

@@ -2,7 +2,7 @@
   <Import Project="..\..\build\common.props" />
 
   <PropertyGroup>
-    <TargetFrameworks>netcoreapp2.0;net461</TargetFrameworks>
+    <TargetFrameworks>netcoreapp2.0</TargetFrameworks>
     <TargetFrameworks Condition=" '$(OS)' != 'Windows_NT' ">netcoreapp2.0</TargetFrameworks>
     <PackageTargetFallback Condition=" '$(TargetFramework)' == 'netcoreapp2.0' ">$(PackageTargetFallback);portable-net451+win8</PackageTargetFallback>