MJExtension是JSON和Model转换最快、最方便以及最易用的框架。（作者：@M了个J ）

功能
JSON --> Model
JSONString --> Model
Model --> JSON
JSON Array --> Model Array
JSONString --> Model Array
Model Array --> JSON Array
Supprting CoreData Objects

MJExtension、JSONModel以及Mantle之间的不同
转换率
MJExtension > JSONModel > Mantle
创建demo并测试
如何使用
JSONModel：You must let all model class extends JSONModel class.
Mantle：You must let all model class extends MTModel class.
MJExtension：Your model class dont't need to extends another base class. Nonintrusive, convenient.