Move sky/examples to sky/sdk/lib/example, and code changes to support that change. Fixes T277.

sky/examples/widgets/container.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 'package:sky/rendering/box.dart';
-import 'package:sky/rendering/flex.dart';
-import 'package:sky/widgets/raised_button.dart';
-import 'package:sky/widgets/basic.dart';
-
-class ContainerApp extends App {
-  Widget build() {
-    return new Flex([
-        new Container(
-          padding: new EdgeDims.all(10.0),
-          margin: new EdgeDims.all(10.0),
-          decoration: new BoxDecoration(backgroundColor: const Color(0xFFCCCCCC)),
-          child: new Image(
-            src: "https://www.dartlang.org/logos/dart-logo.png",
-            size: new Size(300.0, 300.0)
-          )
-        ),
-        new Container(
-          decoration: new BoxDecoration(backgroundColor: const Color(0xFFFFFF00)),
-          padding: new EdgeDims.symmetric(horizontal: 50.0, vertical: 75.0),
-          child: new Flex([
-            new RaisedButton(
-              child: new Text('PRESS ME'),
-              onPressed: () => print("Hello World")
-            ),
-            new RaisedButton(
-              child: new Text('DISABLED'),
-              onPressed: () => print("Hello World"),
-              enabled: false
-            )
-          ])
-        ),
-        new Flexible(
-          child: new Container(
-            decoration: new BoxDecoration(backgroundColor: const Color(0xFF00FFFF))
-          )
-        ),
-      ],
-      direction: FlexDirection.vertical,
-      justifyContent: FlexJustifyContent.spaceBetween
-    );
-  }
-}
-
-void main() {
-  runApp(new ContainerApp());
-}