Remove dependency on JSONKit as Cordova iOS 2.4.0 dropped support for iOS 4.x and now uses NSJSONSerialization. See http://shazronatadobe.wordpress.com/2013/02/08/whats-new-in-cordova-ios-2-4-0/
Fix mutability issues by removing unnecessary mutability and creating mutable copies where needed.
Merge pull request #31 from fuseelements/cdv-2.4+

fix(ios): remove JSONKit, fix mutability issues (fixes #27)