Potential fix for current robot state incorrect

updates should always happen here (they are throttled in current state monitor anyway). 

This should fix #405 - the issue was the following:

(1) current_state_monitor will not pass updates on if none of the joints have changed values. industrial simulator publishes updates at 10 Hz. 
(2) planning_scene_monitor will not process a state update if they are not spaced apart by at least dt_state_update_ which defaults to 0.1s. So, the last state update never gets processed when being used with industrial robot simulator. 
(3) Changing the dt_state_update is not right either since planning_scene_monitor can still miss some updates

Solution is to not use dt_state_update but do an update in planning_scene_monitor everytime current_state_monitor updates - note that this could potentially cause issues if current_state updates come in too fast.