Fix notebook example.

examples/notebook/index.html

@@ -7,7 +7,7 @@
     <script id='jupyter-config-data' type="application/json">
       {{ config_data|tojson }}
     </script>
-    <script src="{{base_url}}example/bundle.js"></script>
+    <script src="{{config_data['frontendUrl']}}bundle.js"></script>
 
     <script type="text/javascript">
       /* Remove token from URL. */

examples/notebook/main.py

@@ -33,7 +33,7 @@ class ExampleHandler(IPythonHandler):
             'baseUrl': self.base_url,
             'token': self.settings['token'],
             'notebookPath': 'test.ipynb',
-            'frontendUrl': ujoin(self.base_url, 'build/'),
+            'frontendUrl': ujoin(self.base_url, 'example/'),
             # FIXME: Don't use a CDN here
             'mathjaxUrl': "https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.5/MathJax.js",
             'mathjaxConfig': "TeX-AMS_CHTML-full,Safe"