Topo2: Improved extensibility of Collections

Change-Id: I07f48e8d4bb74e4ebee78690ac2b102609c4f16d
diff --git a/web/gui/src/main/webapp/app/view/topo2/topo2Collection.js b/web/gui/src/main/webapp/app/view/topo2/topo2Collection.js
index 369da23..c3662e6 100644
--- a/web/gui/src/main/webapp/app/view/topo2/topo2Collection.js
+++ b/web/gui/src/main/webapp/app/view/topo2/topo2Collection.js
@@ -31,6 +31,8 @@
         this.models = [];
         this._reset();
 
+        this.initialize.apply(this, arguments);
+
         if (opts.comparator) {
             this.comparator = opts.comparator;
         }
@@ -42,6 +44,7 @@
 
     Collection.prototype = {
         model: Model,
+        initialize: function () {},
         addModel: function (data) {
             if (Object.getPrototypeOf(data) !== Object.prototype) {
                 this.models.push(data);