finish removing prettify

IPython/frontend/html/notebook/templates/notebook.html

@@ -208,7 +208,6 @@ class="notebook_app"
 <script src="{{ static_url("components/marked/lib/marked.js") }}" charset="utf-8"></script>
 <script src="{{ static_url("components/highlight.js/build/highlight.pack.js") }}" charset="utf-8"></script>
 
-<script src="{{ static_url("prettify/prettify.js") }}" charset="utf-8"></script>
 <script src="{{ static_url("dateformat/date.format.js") }}" charset="utf-8"></script>
 
 <script src="{{ static_url("js/events.js") }}" type="text/javascript" charset="utf-8"></script>