适配IOS7常见需修改的地方：
/Volumes/data2/project/test/CaptionView.m:51:28: 'UITextAlignmentCenter' is deprecated: first deprecated in iOS 6.0
/Volumes/data2/project/test/CaptionView.m:52:28: 'UILineBreakModeWordWrap' is deprecated: first deprecated in iOS 6.0
UITextAlignmentCenter 修改成 NSTextAlignmentCenter
UILineBreakModeWordWrap 修改成 NSLineBreakByWordWrapping