Add dependency on TransitionKit for state machines
Add state machine for easily implementing concurrent NSOperation subclasses
Add `performBlockAndWait:` invocation to RKFetchRequestManagedObjectCache
Drop parentOperation association and set concurrency limit to 1 on `connectionQueue` in `RKManagedObjectImporter`
Drop concurrency limit configuration from debugging
Implment dealloc to try and fight cxx_destruct crashes due to deallocation ordering
Rename `operationQueue` to `dispatchQueue` for clarity. Remove locking around execution block as it can lead to a deadlock.
Port `RKObjectRequestOperation` to a concurrent `NSOperation` subclass backed by a TransitionKit state machine. refs #1137 refs #1247 fixes #1076
Eliminate all usage of `waitUntilFinished` within object request operations. fixes #1137
Remove caveats in documentation regarding deadlocking due to non-concurrent operations
Rework operation callbacks such that response mapping is not completed until the object request operation has an opportunity to perform post-processing. This should eliminate the potential for race conditions that can lead to duplicate object creation during concurrent requests. refs #1329, #1137
Switch AFN dependency from 1.2.1 to ~> 1.2.0. closes #1354
Merge branch 'feature/concurrent-operations' into development