Consider allowing whitelist with offline mode

I see that whitelist is not allowed in offline mode and imagine that's because it's too easy to get past whitelist by 'spoofing' a GamerTag if user isn't required to be logged in to Xbox Live.  However, I think the reasoning is bad. Yes, whitelist in offline mode is not safe. But it is safer than offline mode without whitelist. Currently, server users who want to allow non-logged players will likely just proceed without a whitelist.