Draggable Demos: Update draggable demo to use Polymer PointerEvents polyfill

Author: kborchers

demos/draggable/default.html

@@ -7,6 +7,7 @@
 	<script src="../../jquery-1.9.1.js"></script>
 	<script src="../../ui/jquery.ui.core.js"></script>
 	<script src="../../ui/jquery.ui.widget.js"></script>
+	<script src="../../external/pointerevents.js"></script>
 	<script src="../../ui/jquery.ui.interaction.js"></script>
 	<script src="../../ui/jquery.ui.draggable.js"></script>
 	<link rel="stylesheet" href="../demos.css">