katana: katana_gripper_grasp_controller now provides control_msgs/GripperCommand

In order to work on MoveIt! the gripper is required to provide the GripperCommand action, instead of the previously used GraspHandPostureExecutionAction.

katana_teleop: The katana_teleop_key node has been adapted to the above changes and now sends GripperCommands in order to open/close the gripper.