Updated examples/Quadrotor to use RigidBodyTree::body(int)
Updated examples/Quadrotor to use RigidBodyTree::body(int)

sheim/drake,billhoffman/drake,sheim/drake,billhoffman/drake,billhoffman/drake,sheim/drake,sheim/drake,sheim/drake,sheim/drake,billhoffman/drake,billhoffman/drake,sheim/drake,billhoffman/drake,billhoffman/drake,sheim/drake,billhoffman/drake