AFSwiftDateExtension NSDate 扩展

AFSwiftDateExtension是iOSNSDate扩展，能使NSDate相关操作更简单，它依靠SWIFT顶层函数建立，有更好的体验和安全性。

特性：

Comparedatesusingcommoncompareoperators:>,>=,<,<=

Getintervalbetweendatesusingthatcustomoperator>-<

Add/removedatecomponentsbyusingaritmethicoperators:+,-,+=,-=

Curryedfunctions

Usesubscriptingtoaccesssingleorgroupofdatecomponents

要求：

iOS7orabove

Swift1.2