Merge branch 'release/v0.20.0-rc1'
Merge branch 'release/0.20.0'
Drop pre from README.md install instructions
Fix CocoaPods build warning "`preferred_dependency` has been renamed to `default_subspec`."
Remove obtaining permanent managedObjectID when adding newly created object to the in memory cache. refs #1329
Style tweak in `dispatch_async` of completion blocks
Fix assertion error while copying RKEntityMapping with connections.
Merge pull request #1342 from chebur/development

Fix assertion error while copying RKEntityMapping having non empty connections.
Bump CocoaPods dep to 0.18.1
Bump all dependencies except for OCMock as the class mocking in 2.1.1 does not seem to work for RK test cases
Bump AFNetworking dependencies to 1.2.1
Port to OCMock 2.1.1 mainline
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