Minor optimizations

Author: ENikS

tests/ServiceLocation.Tests.csproj

@@ -8,7 +8,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.7.0-preview-20180307-01" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.7.0" />
     <PackageReference Include="MSTest.TestAdapter" Version="1.3.0-beta2" />
     <PackageReference Include="MSTest.TestFramework" Version="1.3.0-beta2" />
     <ProjectReference Include="..\src\Unity.ServiceLocation.csproj" />