fix view hierarchy in PSCollectionViewController
fix view hierarchy in PSCollectionViewController

Amnysia/PSTCollectionView,niuxinghua/PSTCollectionView,thevuuranusls/PSTCollectionView,steipete/PSTCollectionView,godLoveLucifer/PSTCollectionView,zjh171/PSTCollectionView,CorzFree/PSTCollectionView,ba01ei/PSTImprovedCollectionView,StephaneDelcroix/PSTCollectionView,jianwoo/PSTCollectionView,Anish-kumar-dev/PSTCollectionView,Kevin775263419/PSTCollectionView,zace-yuan/PSTCollectionView,StephaneDelcroix/PSTCollectionView