Event.m:
Added sorting coder methods

FavoritesCell:
Implemented favorites table view

EventsByNameViewController.m:
Removed retrieveData method
Added call to AppDelegate for getting eventsArray

EventDetailsViewController.m:
Added call to AppDelegate to update Favorites list
Added IBAction for favorites button

FavoriteEventsViewController:
Implemented favorites table view

AppDelegate:
Added eventsArray and favoritesArray
Added retrieveData method (moved from EventsByNameViewController)