Move example fn widgets into sky/framework/components

sky/framework/components/toolbar.dart

-part of widgets;
+// 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 '../fn.dart';
+import '../theme/colors.dart';
+import '../theme/shadows.dart';
 
 class Toolbar extends Component {
-
   List<Node> children;
 
   static final Style _style = new Style('''
     display: flex;
     align-items: center;
     height: 56px;
     z-index: 1;
     background-color: ${Purple[500]};
     color: white;
     box-shadow: ${Shadow[2]};'''
   );
 
   Toolbar({String key, this.children}) : super(key: key);
 
   Node build() {
     return new Container(
       style: _style,
       children: children
     );
   }
 }