Squashed commit of the following:

commit ae493edadcce0b3dd7d0c737ef1611a9c5c313f6
Author: Mattt Thompson <m@mattt.me>
Date:   Tue Aug 12 12:29:47 2014 -0700

    Renaming AFNetworkingOperationFailingURLResponseOriginalDataErrorKey to AFNetworkingOperationFailingURLResponseDataErrorKey

commit 09cf2f758748fe753757af25b9185eb552419708
Merge: efaa26d 66c0736
Author: Mattt Thompson <m@mattt.me>
Date:   Tue Aug 12 12:29:02 2014 -0700

    Merge branch 'getOriginalData' of github.com:yageek/AFNetworking into yageek-getOriginalData

commit 66c07365ad82663e28c76b6cefb15adf6cac2ddb
Author: Yannick Heinrich <yannick.heinrich@gmail.com>
Date:   Thu Jul 24 16:08:29 2014 +0200

    Retrieve data on response deserialisation error

    Add new constant
    `AFNetworkingOperationFailingURLResponseOriginalDataErrorKey` to
    retrieve the original data from the request when the response is
    considered  invalid