VideoSubscriberAccount iOS 10.3 to 11.0 API Differences

VSAccountManager.h
Added -[VSAccountManagerDelegate accountManager:shouldAuthenticateAccountProviderWithIdentifier:]
VSAccountMetadataRequest.h
Added VSAccountMetadataRequest.featuredAccountProviderIdentifiers
VSSubscription.h
Added VSSubscriptionAccessLevel
Added VSSubscriptionAccessLevelUnknown
Added VSSubscriptionAccessLevelFreeWithAccount
Added VSSubscriptionAccessLevelPaid
Added VSSubscription
Added VSSubscription.expirationDate
Added VSSubscription.accessLevel
Added VSSubscription.tierIdentifiers
VSSubscriptionRegistrationCenter.h
Added VSSubscriptionRegistrationCenter
Added +[VSSubscriptionRegistrationCenter defaultSubscriptionRegistrationCenter]
Added -[VSSubscriptionRegistrationCenter setCurrentSubscription:]