Change buttonGroup API to accept various information in data parameter

Change-Id: I0c3eb998d9be04fd1e7955b6c412277ec44755aa
diff --git a/dev/js/src/tutorial.js b/dev/js/src/tutorial.js
index fe224b5..2420707 100644
--- a/dev/js/src/tutorial.js
+++ b/dev/js/src/tutorial.js
@@ -139,7 +139,7 @@
         );
 
         var that = this;
-        btn.add(loc.CLOSE, ['button-icon','close'], function () {
+        btn.add(loc.CLOSE, {'cls':['button-icon','close']}, function () {
           element.style.display = 'none';
         });
         element.appendChild(btn.element());