[pr2eus] :go-pos-unsafe always returns nil in kinematics simualtion and cmd_vel case

[knorth55]

:go-pos-unsafe always returns nil in kinematics simulation or cmd_vel case.
:go-pos-unsafe-no-wait returns t but :go-pos-unsafe-wait returns nil, thats why :go-pos-unsafe returns nil.

jsk_pr2eus/pr2eus/robot-interface.l

Lines 1699 to 1701 in d2d28d2

	(:go-pos-unsafe (&rest args)
	(send* self :go-pos-unsafe-no-wait args)
	(send self :go-pos-unsafe-wait))

I supposed that :go-pos-unsafe should return t if the motion works correctly.

[knorth55]

:go-pos-unsafe only returns t or nil when move_base_trajectory_action is enable and the action succeeded to run the motion.