Support precise jog

[7675t]

This PR improve the controller to move precisely even the robot doesn't move with high gain controller. See #11 .

• The controller keep the start robot state
• The controller uses the start state to append jog command
• When jog command is absence for longer than timeout (time_from_start), the start state should be resetted
• jog publishing nodes (such as rviz panel plugin) must stop to publish when the jog is all zero to reset the start state