Update datejs CDN to a faster/more reliable one

whats_open/templates/head.html

@@ -6,7 +6,7 @@
 <link href="{{ STATIC_URL }}css/style.css" rel="stylesheet">
 <script src="//ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>
 <script src="//ajax.googleapis.com/ajax/libs/jqueryui/1.10.2/jquery-ui.min.js"></script>
-<script type="text/javascript" src="http://www.datejs.com/build/date.js"></script>
+<script src="//cdnjs.cloudflare.com/ajax/libs/datejs/1.0/date.min.js"></script>
 <script src="{{ STATIC_URL }}js/bootstrap.min.js"></script>
 <script src="{{ STATIC_URL }}js/grid.js"></script>
 <script src="{{ STATIC_URL }}js/typeAhead.js"></script>