http://www.raywenderlich.com/forums/viewtopic.php?f=2&t=2000
http://www.ibm.com/developerworks/library/mo-ios-push/
https://github.com/hollyschinsky/PushNotificationSample
http://iosapplove.com/archive/2012/10/apns-tutorial-how-to-send-pushnotifications-to-my-app/
http://iosapplove.com/archive/2013/01/apns-tutorial-how-to-send-pushnotifications-to-my-iphone-ipad-app-part-2/
http://iosapplove.com/archive/2013/01/apns-tutorial-how-to-send-pushnotifications-to-my-iphone-ipad-app-part-3/