TC-4671 - iOS8: currentUserNotificationSettings & didRegisterUserNotificationSettings

TC-4671 - iOS8: Access to currentUserNotificationSettings & didRegisterUserNotificationSettings

Add ability to get notification types registered in [UIApplication sharedApplication] currentUserNotificationSettings.
Add ability to recieve an event when didRegisterUserNotificationSettings fires

For details please see https://jira.appcelerator.org/browse/TC-4671
For approach document, please see https://gist.github.com/benbahrenburg/7b65d074c728cba0de4c