[NEW] ImageController's getImage method refactored to take a FeedItem, it will help with stats.
[NEW] FeedImageItems now created for each downloaded image to store their sizes, etc.
[NEW] Augmented first load to only store the 300 FeedItems once and to return them from Core Data if we've already got them.
[NEW] Stats now generated from whatever data has been stored by the time the user reaches the bottom.