Fixed issue on -shouldInvalidateLayoutForBoundsChange:

Now the collection view asks the layout wether it should invalidate, before actually changing the frame or bounds of the collection view.

I noticed that when using a UICollectionView, and rotating the device, the method got called before the rotation occurred, handing the new frame on the argument. Thus I made a simple comparison, if the widths changed, then return YES.

When testing the same code in the PSTCollectionView, I noticed the layout didn't invalidate, and after debugging, I realized that the method was being called with the new self.bounds, checking the source code, I noticed the issue, and corrected it.