Fix chat view may not display chat content

修复私信聊天界面在收入内容后退出界面再重新进入，有时
无法看到之前输入的内容
Fix that sometimes "imageWithContentsOfFile" can't find "@2x" file
New UI of birthday view and visitor view
Fix in iOS5 using cornerRadius must import QuartzCore.h
Make it compatible with iOS5