Updated build script to target specific test projects

Author: shealey

appveyor.yml

@@ -14,4 +14,5 @@ build:
   verbosity: minimal
 
 test_script:
-  - cmd: dotnet test
+  - cmd: dotnet test samples\FluentAssertions.AspNetCore.Mvc.Sample.Tests\FluentAssertions.AspNetCore.Mvc.Sample.Tests.csproj
+  - cmd: dotnet test tests\FluentAssertions.AspNetCore.Mvc.Tests\FluentAssertions.AspNetCore.Mvc.Tests.csproj