Extend VisualStudio.gitignore by $tf1

Usually $tf1 cache folder is created for init a TFS project.
But the $tf1 is created when you connect to your team project after renaming.
On the next renaming the $tf2 is created, so it makes sense to ignore $tf1 to $tf9.

VisualStudio.gitignore

@@ -123,6 +123,7 @@ ipch/
 
 # TFS 2012 Local Workspace
 $tf/
+$tf[1-9]/
 
 # Guidance Automation Toolkit
 *.gpState