Fix missed bundler -> bundlerextensions renames

In notebook.json config

(c) Copyright IBM Corp. 2016

notebook/bundler/handlers.py

@@ -37,7 +37,7 @@ class BundlerHandler(IPythonHandler):
             If the bundler ID is unknown
         """
         cm = ConfigManager()
-        return cm.get('notebook').get('bundlers', {})[bundler_id]
+        return cm.get('notebook').get('bundlerextensions', {})[bundler_id]
 
     @web.authenticated
     @gen.coroutine

notebook/static/notebook/js/menubar.js

@@ -73,7 +73,7 @@ define([
     MenuBar.prototype.add_bundler_items = function() {
         var that = this;
         this.config.loaded.then(function() {
-            var bundlers = that.config.data.bundlers;
+            var bundlers = that.config.data.bundlerextensions;
             if(bundlers) {
                 // Stable sort the keys to ensure menu items don't hop around
                 var ids = Object.keys(bundlers).sort()