Added require.js shims for underscore and backbone

This is necessary since underscore and backbone are no longer AMD
modules.

IPython/html/static/notebook/js/widgetmanager.js

@@ -21,8 +21,8 b''
     // Use require.js 'define' method so that require.js is intelligent enough to
     // syncronously load everything within this file when it is being 'required' 
     // elsewhere.
-    define(["components/underscore/underscore-min",
-             "components/backbone/backbone-min",
+    define(["underscore",
+             "backbone",
             ], function (underscore, backbone) {
 
         //--------------------------------------------------------------------

IPython/html/static/notebook/js/widgets/base.js

@@ -15,8 +15,8 b''
  **/
 
 define(["notebook/js/widgetmanager",
-        "components/underscore/underscore-min",
-        "components/backbone/backbone-min"], 
+        "underscore",
+        "backbone"], 
 function(widget_manager, underscore, backbone){
     
     //--------------------------------------------------------------------

IPython/html/templates/page.html

@@ -21,7 +21,18 b''
       require.config({
           baseUrl: '{{static_url("")}}',
           paths: {
-            nbextensions : '{{ base_project_url }}nbextensions'
+            nbextensions : '{{ base_project_url }}nbextensions',
+            underscore : '{{static_url()}}components/underscore/underscore-min',
+            backbone : '{{static_url()}}components/backbone/backbone-min', 
+          },
+          shim: {
+            underscore: {
+              exports: '_'
+            },
+            backbone: {
+              deps: ["underscore", "jquery"],
+              exports: "Backbone"
+            }
           }
       });
     </script>