title: Pre-installed data on LongListSellector
body: <p>I've got an ObservableCollection which is binded to my LongListSelector.<br>
  User can add items to it by form in my app - all data saved in list are serialized.<br>
  I want to add few items to my app, that will be present after installation. User can delete and modify them, like any other items.<br>
  What is the best way to do that? I don't think that creating multiple objects in code is good idea.</p>