Fixed broken links to moment.js

examples/timeline/02_dataset.html

@@ -20,7 +20,7 @@
     </style>
 
     <!-- note: moment.js must be loaded before vis.js, else vis.js uses its embedded version of moment.js -->
-    <script src="https://rawgithub.com/moment/moment/2.2.1/min/moment.min.js"></script>
+    <script src="http://cdnjs.cloudflare.com/ajax/libs/moment.js/2.3.1/moment.min.js"></script>
 
     <script src="../../vis.js"></script>
 </head>

examples/timeline/03_much_data.html

@@ -11,7 +11,7 @@
     </style>
 
     <!-- note: moment.js must be loaded before vis.js, else vis.js uses its embedded version of moment.js -->
-    <script src="https://rawgithub.com/moment/moment/2.2.1/min/moment.min.js"></script>
+    <script src="http://cdnjs.cloudflare.com/ajax/libs/moment.js/2.3.1/moment.min.js"></script>
 
     <script src="../../vis.js"></script>
 </head>

examples/timeline/05_groups.html

@@ -17,7 +17,7 @@
     </style>
 
     <!-- note: moment.js must be loaded before vis.js, else vis.js uses its embedded version of moment.js -->
-    <script src="https://rawgithub.com/moment/moment/2.2.1/min/moment.min.js"></script>
+    <script src="http://cdnjs.cloudflare.com/ajax/libs/moment.js/2.3.1/moment.min.js"></script>
 
     <script src="../../vis.js"></script>
 </head>