Added fix for UIScrollView issues with autolayout.

So, as I medtioned in issue #5 there are some troubles with iOS 8. It turned out that this can be easily fixed by inspecting constraints. Some of them (those responisble for resizing `UIImageView`) has pinned `imageView` as a second view and `scrollView` as a first view - it should be reversed. It's strange because iOS 7 doesn't have any problems with translating those.