work around import error
work around import error

see: https://github.com/RobotLocomotion/director/pull/85#issuecomment-148117827

openhumanoids/director,manuelli/director,patmarion/director,patmarion/director,patmarion/director,openhumanoids/director,mitdrc/director,patmarion/director,openhumanoids/director,RobotLocomotion/director,RobotLocomotion/director,mitdrc/director,manuelli/director,openhumanoids/director,mitdrc/director,RobotLocomotion/director,patmarion/director,manuelli/director,mitdrc/director,RobotLocomotion/director,manuelli/director,openhumanoids/director,manuelli/director,RobotLocomotion/director,mitdrc/director