Improved notification

Useful reference:

* https://developer.android.com/training/wearables/notifications/stacks.html
* https://developer.android.com/reference/android/support/v4/app/NotificationCompat.WearableExtender.html#addPages(java.util.List<android.app.Notification>)
* https://developer.android.com/training/wearables/notifications/creating.html