Prevent annoying changes to unit test projects by VS2013

by simply opening each solution in VS2013, then compiling, the ItemGroup/Service/Include section is added. According to the following link, VS2013 'tags' unit test projects with these markers to help improve startup time with third-party testing tools. http://connect.microsoft.com/VisualStudio/feedback/details/800245/vs2013rc-adds-to-vs2012-c-project-section-itemgroup