if self.objectIdentifiers = nil predicate will fail.
Merge pull request #113 from MIT-Mobile/3.6/ipad-news-update-stories

3.6/ipad news update stories
Before code was displaying all stories in store.  We just want ones we searched for.
Merge pull request #114 from MIT-Mobile/3.6/ipad-news-search-fix

if objectIdentifiers is nil, the fetch will crash.
Fixes a bug where new stories would not be displayed immediately after being updated
Initial commit of the category data source
Changes for the category data source
Tweaks to the fetched results controller setup process
Clean up the self references and unlock the lock
Merge pull request #125 from MIT-Mobile/3.6/news-cached-categories

3.6/news cached categories
Add a copy initializer NSIndexPath
Merge branch 'refs/heads/3.6/ipad-news' into 3.6/ipad-news-tableview-height-estimation
Using new NSIndexPath category.

Changes suggested by @bskinner