Don't create unnecessary objects when mapping temporary managed objects POST'd without identification attributes. closes #1149
Fix issues with mapping errors from 5xx payloads. Ensure `acceptableStatusCodes` tracks the status codes configured in the response descriptors. fixes #1157
Fix bug with status code handling when `statusCodes` is `nil` for any response descriptor.
Add test case for unexpected NSSet. #1118
Fix issue in which managed objects that are the children of non-managed objects were refetched and assigned as a collection rather than as a singular value. fixes #1118
Add support for transforming strings 'Y' and 'N' to boolean NSNumber objects
Add unit tests for mapping 'n' and 'y' characters as Boolean values. refs #1151
Fix crash when mapping to `NSManagedObject` class with Transformable attribute without a backing property. fixes #1162
Fix crash when serializing `NSDate` properties mapped at nested keypaths. fixes #1134
Fix bug with mapping nested attribute values with identification attributes when the identification attribute is not the nesting key. fixes #1129
Rework implementation of cyclic mapping graph traversal. refs #1142 #1158 #1163
Add test coverage verifying fix for crash during cyclic graph traversal in `RKManagedObjectRequestOperation`. closes #1142
Add temporary workaround for infinite recursion
Radically simplify the implementation of managed object deletion and refetching within `RKManagedObjectRequestOperation`. closes #1163

1. Eliminates use of visitor in favor of aggregating mapping info during mapping. This avoids having to traverse the mapping graph.
1. Eliminate special case handling of cyclic key paths.
1. Eliminate issues with infinite recursion while traversing the mapping graph.
Remove unnecessary exception handling for `NSUndefinedKeyException`
Copy `attributeCaches` to avoid potential for mutation during enumeration
Encapsulate managed object refetching into an NSProxy object to enable you to defer the refetching until the mapping result is accessed (or skip it entirely if the result is not accessed)
Nil out `targetObjectID` if given a `targetObject` that is not an `NSManagedObject`. closes #1161
Add test case for empty 5xx response. refs #1169
Fix failed assertion when constructing an unprocessable response error for 5xx errors. closes #1169