[FIX] gamification: do not overwrite the mail widget as it would be called too often, the wall is enough

bzr revid: mat@openerp.com-20140425130740-ptkbsyyql08cx572

addons/gamification/static/src/js/gamification.js

@@ -126,7 +126,7 @@ openerp.gamification = function(instance) {
         }
     });
 
-    instance.mail.Widget.include({
+    instance.mail.Wall.include({
         start: function() {
             this._super();
             var sidebar = new instance.gamification.Sidebar(this);