A solution item template that creates a default runsettings file under Solution Items, and saves you from having to do this manually. Seehttp://msdn.microsoft.com/en-us/library/vstudio/jj159530.aspx for information on how to change the default settings.
The runsettings file is used to change the code coverage analysis settings for a test run, in particular which files to be included and excluded from analysis, and also used to set symbol search paths.
See this blogpost for more information : http://geekswithblogs.net/terje/archive/2013/12/04/how-to-exclude-code-from-code-coverage-in-visual-studio.aspx
VS 2013 version: /vsgallery/704ebd18-7d60-4341-9224-532f73229c74
VS 2015 version: /vsgallery/1cc3863b-f15f-4107-bb05-3586fd65540b