Use UICollectionView rather than AQGridView
Update to iOS6 minimum version (as lower versions don't have UICollectionView).
Suggest https://github.com/steipete/PSTCollectionView/tree/master/PSTCollectionView if support for older versions is required.
Fix warnings 'created' by making iOS6 minimum version.
Padding is different using UICollectionView to AQGridView.
Merge branch 'uicollectionview' of git://github.com/sdarlington/baker into sdarlington-uicollectionview

Conflicts:
	BakerShelf/ShelfViewController.h
	BakerShelf/ShelfViewController.m
	BakerView/BakerViewController.m
Merge commit '63c64d6f44155e2634bd285ba4a37180edf81f10' into newsstand_notification

Conflicts:
	Baker.xcodeproj/project.pbxproj
	BakerShelf/IssueViewController.m