Widget: Update demos for new file structure

Author: arschmitz

demos/widget/default.html

@@ -8,7 +8,7 @@
 	<script src="../../ui/core.js"></script>
 	<script src="../../ui/position.js"></script>
 	<script src="../../ui/widget.js"></script>
-	<script src="../../ui/button.js"></script>
+	<script src="../../ui/widgets/button.js"></script>
 	<link rel="stylesheet" href="../demos.css">
 	<style>
 	.custom-colorize {