Added nuget dependency on xunit.runner.visualstudio.

Author: alexanderfast

src/CommandLine.Tests/packages.config

@@ -7,4 +7,5 @@
   <package id="xunit.core" version="2.0.0" targetFramework="net45" />
   <package id="xunit.extensibility.core" version="2.0.0" targetFramework="net45" />
   <package id="xunit.extensions" version="2.0.0" targetFramework="net45" />
+  <package id="xunit.runner.visualstudio" version="2.0.0" targetFramework="net45" />
 </packages>