One potential solution for you is to add a head set with a rotor onto your bicycle. It is a small contraption that allows you to keep your brakes and still be able to spin your handlebars all the way around. I no longer know how much these systems cost, but a guess would be $30 to $50 just for the parts and add about maybe $20 for installation. There are of course plenty of new bikes that already have this installed.
Another possible solution is to just replace your brake cable with one that is extra long that will allow you to spin the bars. While this option will not be *ideal* for braking performance and you will have to spin your bars back once you are done with a trick, it will work. Besides, bike brakes with rotors are kind of lacking in performance anyways.