Add Cards and Fitness demos, remove sector.

sky/sdk/example/widgets/card_collection.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/base/lerp.dart';
 import 'package:sky/painting/text_style.dart';
 import 'package:sky/theme/colors.dart';
 import 'package:sky/widgets/basic.dart';
 import 'package:sky/widgets/card.dart';
 import 'package:sky/widgets/dismissable.dart';
 import 'package:sky/widgets/scaffold.dart';
 import 'package:sky/widgets/variable_height_scrollable.dart';
 import 'package:sky/widgets/theme.dart';
 import 'package:sky/widgets/tool_bar.dart';
 import 'package:sky/widgets/widget.dart';
+import 'package:sky/theme/colors.dart' as colors;
+import 'package:sky/widgets/task_description.dart';
 
 
 class CardCollectionApp extends App {
 
   final TextStyle cardLabelStyle =
     new TextStyle(color: white, fontSize: 18.0, fontWeight: bold);
 
   final List<double> cardHeights = [
     48.0, 64.0, 82.0, 46.0, 60.0, 55.0, 84.0, 96.0, 50.0,
     48.0, 64.0, 82.0, 46.0, 60.0, 55.0, 84.0, 96.0, 50.0,
@@ skipping 38 matching lines @@
   Widget build() {
     Widget cardCollection = new Container(
       padding: const EdgeDims.symmetric(vertical: 12.0, horizontal: 8.0),
       decoration: new BoxDecoration(backgroundColor: Theme.of(this).primarySwatch[50]),
       child: new VariableHeightScrollable(
         builder: _builder,
         token: visibleCardIndices.length
       )
     );
 
-    return new Scaffold(
-      toolbar: new ToolBar(center: new Text('Swipe Away')),
-      body: cardCollection
+    return new Theme(
+      data: new ThemeData(
+        brightness: ThemeBrightness.light,
+        primarySwatch: colors.Blue,
+        accentColor: colors.RedAccent[200]
+      ),
+      child: new TaskDescription(
+        label: 'Cards',
+        child: new Scaffold(
+          toolbar: new ToolBar(center: new Text('Swipe Away')),
+          body: cardCollection
+        )
+      )
     );
   }
 }
 
 void main() {
   runApp(new CardCollectionApp());
 }