Use ListView in widget (only enabled for android honeycomb or higher)

I thought it would be nice to have a listview in the widget.  It saves space (the buttons are not necessary anymore) and also multi-line items are displayed better.
Unfortunately it is only supported for android honeycomb or higher, so I kept the old widget for older versions.

The first commit in this pull request also adds some other functionality in the widget, see git-comments there