Change buttonGroup API to accept various information in data parameter

Change-Id: I0c3eb998d9be04fd1e7955b6c412277ec44755aa
diff --git a/dev/demo/panel.html b/dev/demo/panel.html
index 5782365..ea8f57d 100644
--- a/dev/demo/panel.html
+++ b/dev/demo/panel.html
@@ -28,7 +28,7 @@
   let actions = panel.actions;
 
   // Add simple button
-  actions.add('Meta',['meta'], function () {
+  actions.add('Meta',{'cls':['meta']}, function () {
     console.log(this.button.classList.contains('meta'));
     view = kqClass.create();
     panel.add(view);