Switch to netcoreapp1.1 and net462 for tests

Author: Jos Hickson

Winton.Extensions.Threading.Actor.Tests.Unit/Winton.Extensions.Threading.Actor.Tests.Unit.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>    
-    <TargetFrameworks>netcoreapp1.0;net451</TargetFrameworks>
+    <TargetFrameworks>netcoreapp1.1;net462</TargetFrameworks>
     <SignAssembly>True</SignAssembly>    
     <DelaySign>False</DelaySign>    
     <AssemblyOriginatorKeyFile>../keys/Winton.Extensions.Threading.Actor.snk</AssemblyOriginatorKeyFile>