* Factored out display of alerts into RKAlert interface that hides the differences between UIKit and OS X Cocoa.
* Added macosx to supported platforms to enable build on OS X.
* Configured project to use conditional architectures to enable building on OS X and iOS from the same targets.
* Implemented a bare-bones OS X example app.
* Create `rake build` task for building RestKit against iOS and OS X SDK for quick testing.
Introduces four modes for handling background requests:
* RKRequestBackgroundPolicyNone - The default behavior replicating pre-background behavior. No special action is taken with regards to backgrounding.
* RKRequestBackgroundPolicyCancel - On transition to the background, requests with this policy set will be cancelled automatically and the delegate informed.
* RKRequestBackgroundPolicyContinue - Requests with this policy will be continued in the background after the app has been transitioned.
* RKRequestBackgroundPolicyRequeue - Requests with this policy will be cancelled and then immediately placed onto the queue for processing the next time the app is returned to the foreground.
* Updates YAJL Parser not to raise an exception and crash when it encounters invalid JSON. The other parsers need to be aligned with this behavior and the delegate methods updated. See Pivotal Story: https://www.pivotaltracker.com/story/show/11925617
* Added requestDidCancel: delegate invocation for tracking cancellation of requests.
* Ensure that the request queue timer is cleared during indeterminate deferral of request loads.
