WEB UI -- Simplified listener mechanism in theme.js to match that of prefs.js
 - minor cleanup of app.js

Change-Id: I1a05c5cb43c994937747ef69841d24a863128f4d
diff --git a/web/gui/src/main/webapp/app/view/topo/topoInst.js b/web/gui/src/main/webapp/app/view/topo/topoInst.js
index 1d0cbed..22e2b47 100644
--- a/web/gui/src/main/webapp/app/view/topo/topoInst.js
+++ b/web/gui/src/main/webapp/app/view/topo/topoInst.js
@@ -43,12 +43,9 @@
     var onosInstances,
         onosOrder,
         oiShowMaster,
-        oiBox,
-        themeListener;
+        oiBox;
 
 
-    // ==========================
-
     function addInstance(data) {
         var id = data.id;
 
@@ -273,12 +270,11 @@
         oiShowMaster = false;
 
         // we want to update the instances, each time the theme changes
-        themeListener = ts.addListener(updateInstances);
+        ts.addListener(updateInstances);
     }
 
     function destroyInst() {
-        ts.removeListener(themeListener);
-        themeListener = null;
+        ts.removeListener(updateInstances);
 
         ps.destroyPanel(idIns);
         oiBox = null;