Added loaders

Playground/index2_5.html

@@ -22,6 +22,10 @@
     <script src="js/v2.5/babylon.2.5.canvas2d.js"></script>
     <script src="https://www.babylonjs.com/babylon.inspector.bundle.js"></script>
 
+    <script src="https://www.babylonjs.com/lib/babylon.glTFFileLoader.js"></script>
+    <script src="https://www.babylonjs.com/lib/babylon.objFileLoader.js"></script>
+    <script src="https://www.babylonjs.com/lib/babylon.stlFileLoader.js"></script>
+
     <script src="https://rawgit.com/BabylonJS/Extensions/master/ClonerSystem/src/babylonx.cloner.js"></script>
     <link href="css/index.css" rel="stylesheet" />
 </head>