Move examples to //sky/sdk/example

sky/sdk/example/raw/launcher.dart

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 import "dart:math";
 import 'dart:sky';
 
 import 'package:sky/framework/shell.dart' as shell;
 import 'package:mojom/intents/intents.mojom.dart';
 
@@ skipping 37 matching lines @@
   return false;
 }
 
 void main() {
   print("Hello, world");
   view.picture = draw(255, 255, 255, 0);
   view.scheduleFrame();
 
   view.setEventCallback(handleEvent);
 }