Add .vs directory to the .gitignore (Visual Studio 2017 produces this)

(cherry picked from commit fe73a07)

Author: joelverhagen

.gitignore

@@ -215,4 +215,5 @@ tools
 .nuget/NuGet.exe
 .nuget/ThirdPartyNotices.txt
 Results.*.xml
-!**/TestData/*.nupkg
+!**/TestData/*.nupkg
+.vs