Fix to effectively ignoring contentInset with a small contentSize.
Removed the minimum contentSize setter in -[PSTCollectionViewFlowLayout updateItemsLayout].
PSTCVFlowLayout -updateItemsLayout takes into accout PSTGridLayoutSection.sectionMargins to set contentSize.
Merge pull request #177 from loganmoseley/master

-[PSTCollectionViewFlowLayout updateItemsLayout] changes to correct contentSize.