Convert default project template to fn3

packages/flutter_tools/lib/src/init.dart

@@ -141,6 +141,17 @@ dev_dependencies:
 const _libMain = r'''
 import 'package:sky/widgets.dart';
 
-void main() => runApp(new Center(child: new Text('Hello, world!')));
+void main() => runApp(new HelloWorldApp());
+
+class HelloWorldApp extends StatelessComponent {
+  Widget build(BuildContext context)  {
+    return new Scaffold(
+      toolbar: new ToolBar(center: new Text("Flutter Demo")),
+      body: new Material(child: new Center(child: new Text("Hello world!"))),
+      floatingActionButton: new FloatingActionButton(
+        child: new Icon(type: 'content/add', size: 24))
+      );
+  }
+}
 
 ''';