add param to plan safe trajectory on backwards (#13)
see https://github.com/jsk-ros-pkg/jsk_robot/tree/master/jsk_fetch_robot/jsk_fetch_startup for detail select joystick with safe mode : 'rosservice call /cmd_vel_mux/select /safe_teleop_base/safe_vel' select move_base navigation : 'rosservice call /cmd_vel_mux/select /cmd_vel'
Contributors: Yuki Furuta, Kei Okada