When user enters a search query for a ListFragment the query will
now be restored on device configuration changes and when
ListFragment is restored from the backstack or in a ViewPager.
Refactored AbstractListFragment to make it more generic and allow it to be used by
MediaFileListFragment. This adds support for switching between a single- and multicolumn
view.
Created new abstract class AbstractCursorListFragment for list fragments using a cursoradapter.