Passing Errors from AFNetworking calls through to allow failure blocks to execute.
Ensure responseArray isn't nil before casting to an array.
Setting responseObject on userInfo to allow access to response body on failure (ref: https://github.com/AFNetworking/AFNetworking/issues/1397)
Aligning the error initialization for consistency
Added key to access userInfo on error
Using KVC setValue to safely insert data to userInfo without checking for nil
Setting userInfo response from returned data as a string
Merge pull request #45 from bswatson/master

Handle errors and allow AFNetworking 2.0 failure block to execute