Add Cards and Fitness demos, remove sector.

sky/sdk/example/fitness/lib/main.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/theme/colors.dart' as colors;
 import 'package:sky/widgets/basic.dart';
 import 'package:sky/widgets/navigator.dart';
 import 'package:sky/widgets/theme.dart';
 import 'package:sky/widgets/widget.dart';
+import 'package:sky/widgets/task_description.dart';
 
 import 'measurement.dart';
 import 'home.dart';
 import 'settings.dart';
 import 'fitness_types.dart';
 
 class FitnessApp extends App {
 
   NavigationState _navigationState;
 
   void initState() {
     _navigationState = new NavigationState([
       new Route(
-        name: '/', 
+        name: '/',
         builder: (navigator, route) => new HomeFragment(navigator, _userData)
       ),
       new Route(
         name: '/settings',
         builder: (navigator, route) => new SettingsFragment(navigator, backupSetting, settingsUpdater)
       ),
     ]);
     super.initState();
   }
 
@@ skipping 20 matching lines @@
     new Measurement(when: new DateTime.now(), weight: 400.0)
   ];
 
   Widget build() {
     return new Theme(
       data: new ThemeData(
         brightness: ThemeBrightness.light,
         primarySwatch: colors.Indigo,
         accentColor: colors.PinkAccent[200]
       ),
-      child: new Navigator(_navigationState)
+      child: new TaskDescription(
+        label: 'Fitness',
+        child: new Navigator(_navigationState)
+      )
     );
   }
 }
 
 void main() {
   runApp(new FitnessApp());
 }