Removing storyUpdateInProgress from public header.

Updated storiesDataSource requestInProgress to work when requesting more stories.

Updated storyAfterStory in Category view to use getMoreStoriesForSection instead of implementing own fetching of stories.
Changed error.code from -1009 to NSURLErrorNotConnectedToInternet.

Changed addOperationWithBlock to dispatch_get_main_queue.

Added error message when coming back from story detail and more stories are still be loaded but they fail.