Fix for collection view cells not appearing when project is built in Xcode 6 running on iOS 7.

Fix for collection view cells not appearing when project is built in Xcode 6 running on iOS 7.
https://developer.apple.com/library/ios/releasenotes/developertools/rn-xcode/Chapters/Introduction.html.
The '_MyCollectionViewCell' is unnecessary here. Just _commonInit_ is fine.