Add yarn.lock

Author: acjh

.gitignore

@@ -120,4 +120,7 @@ Generated_Code #added for RIA/Silverlight projects
 _UpgradeReport_Files/
 Backup*/
 UpgradeLog*.XML
-src/.vs/config/applicationhost.config
+src/.vs/config/applicationhost.config
+
+# Node.js dependencies
+node_modules/