GUI -- Implemented Instance Panel.
- handling addInstance event.

Change-Id: Ic98a3291bd37ecf1155dbe1696167d0635a31972
diff --git a/web/gui/src/main/webapp/app/fw/layer/panel.js b/web/gui/src/main/webapp/app/fw/layer/panel.js
index 1665626..4df0d72 100644
--- a/web/gui/src/main/webapp/app/fw/layer/panel.js
+++ b/web/gui/src/main/webapp/app/fw/layer/panel.js
@@ -75,7 +75,8 @@
                 append: appendPanel,
                 width: panelWidth,
                 height: panelHeight,
-                isVisible: panelIsVisible
+                isVisible: panelIsVisible,
+                el: panelEl
             };
 
         p.el = panelLayer.append('div')
@@ -136,6 +137,10 @@
             return p.on;
         }
 
+        function panelEl() {
+            return p.el;
+        }
+
         return api;
     }