soffes/sspulltorefresh — pull request #23 by hwaxxer (2013-01-22 17:31:36+00:00)
Title: Fixes issue where scrolling stutters

Setting the contentInset while the UIScrollView is scrolling will make it stutter, and having it depend on the current contentOffset.y will trigger a lot of changes when the user is scrolling.
This fix allows only two insets: 0 or _expandedHeight.