[TIMOB-17640] Adding and updating UserNotification methods

- remoteNotificationsEnabled calls isRegisteredForRemoteNotifications on iOS8 and up
- enabledRemoteNotificationTypes calls currentUserNotificationSettings on iOS8 and up
- method name change registerForLocalNotifications ---> registerUserNotificationSettings
- registerUserNotificationSettings types ---> takes an array
- new property ---> currentUserNotificationSettings
- notification constants in Ti.App.iOS are prefixed with USER_
	- eg. NOTIFICATION_TYPE_BADGE ---> USER_NOTIFICATION_TYPE_BADGE
	- To avoid confusion with similarly named constants in Network.
- TiAppiOSNotificationCategoryProxy ---> properties are creation time only
	- identifier is readable after creation
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
Fix remove issue
[TIMOB-17640] iOS: UserNotificationSettings adding event for when settings are registered
[TIMOB-17640] Loggin warning about passing types to registerForPushNotifications in iOS8+
[TIMOB-17640] CR fixes
Merge pull request #6046 from jonalter/TIMOB-17640

[TIMOB-17640] Adding and updating UserNotification methods