Editor’s note: Sign up for Unlocking the World, CNN Travel’s weekly newsletter . Get news about destinations, plus the latest in aviation, food and drink, and where to stay. CNN  —  When it was first announced four years ago, it sounded like an aviation geek’s dream — an airline with a fleet consisting only of Airbus A380 superjumbos, the huge and majestic double-decker airplanes that offer unrivaled comfort in the sky. Promotional images released by Global Airlines , a startup carrier founded