Jenn6286/issue15 measure display scrollbar items control

This resolves #15 

@hmassih  : Please code-review

Branch was created from v.next with change to MeasureDisplayControl.xaml only.

Changes:
- Removed inner grid that takes row height=auto because this allowed grid to grow without height restriction. 
- Removed ScrollViewer that contained ItemsControl because this is ignored by ItemsControl and set its ControlTemplate to surround ItemsPresenter with ScrollViewer instead.