Make error codes publicly available

[adrianod1as]

Could you make all or some of the codes in NSError+MASPrivate.m publicly available? It would be useful. For instance, I could handle for my needs a timed out request or sudden lack of Internet connection by comparing the error code to your constants.

https://github.com/CAAPIM/iOS-MAS-Foundation/blob/90fb3f4d2a1c23064076cdd5d12e92002a20857e/MASFoundation/Classes/private/categories/NSError%2BMASPrivate.m#L128

Thanks for your attention o/