1.仿照新浪微博Android客户端个人中心的ScrollView，下拉背景伸缩回弹效果。 2.ScrollView仿IOS回弹效果。
A Parallax ScrollView which takes a background and foreground views - DEPRECATED
Android: iOS-like over-scrolling effect applicable over almost all scrollable Android views.
AKParallax-Android is a Library Project that provides a parallax effect to an imageView in a ScrollView or a ListView.
