Add subscriber manager

www/scripts/common/websockets/subscriberManager.js

@@ -0,0 +1,36 @@
+define([
+    "underscore",
+    "backbone",
+    "common/websockets/connection"
+], function (_, Backbone, WSConnection) {
+    var currentTopic = null;
+    var callbackStack = [];
+
+    var callbackHandler = function (topic, msg) {
+        _.each(callbackStack, function(cb) {
+            cb(topic, msg);
+        });
+    };
+
+    var reset = function () {
+        callbackStack = [];
+        currentTopic = null;
+    };
+
+    return {
+        'register': function (topic) {
+            this.unregister();
+            WSConnection.subscribe(topic, callbackHandler);
+            currentTopic = topic;
+        },
+        'unregister': function () {
+            if (currentTopic !== null) {
+                WSConnection.unsubscribe(currentTopic);
+                reset();
+            }
+        },
+        'pushCallback': function (callback) {
+            callbackStack.push(callback);
+        }
+    }
+});