##1 内购流程
http://www.cnblogs.com/helloandroid/p/4613683.html
http://www.jianshu.com/p/e9ae4cece800
http://blog.csdn.net/teng_ontheway/article/details/47011813
##2 iOS 沙盒购买，弹出“需要验证”，“继续登录”的问题？
http://www.cnblogs.com/wanyakun/p/3403357.html
##3 In app purchases restore Button http://stackoverflow.com/questions/11021932/in-app-purchases-restore-button
http://www.cocoachina.com/bbs/read.php?tid=224686