Add .sap Visual Studio profiler session file

In Windows Phone 8 development each profiler session generates a new .sap file, which is automatically added to the root of the project. This is an XML manifest describing the detailed profiler logs created in the PerfLogs folder.

VisualStudio.gitignore

@@ -84,6 +84,7 @@ ipch/
 *.psess
 *.vsp
 *.vspx
+*.sap
 
 # TFS 2012 Local Workspace
 $tf/