message: FIX: Rename gripper -> use_gripper launch argument
diff: <arg name="headless" default="false" doc="Should the gazebo GUI be launched?" />
  <arg name="paused" default="true" doc="Should the simulation directly be started?" />
  <arg name="arm_id" default="panda" doc="Name of the panda robot to spawn" />
  - <arg name="gripper" default="true" doc="Should a franka hand be mounted on the flange?" />
  + <arg name="use_gripper" default="true" doc="Should a franka hand be mounted on the flange?" />
  <arg name="x" default="0" />
  <arg name="y" default="0" />
  arm_id:=$(arg arm_id)
  connected_to:=world
  use_franka_transmissions:=true
  - use_gripper:=$(arg gripper)">
  + use_gripper:=$(arg use_gripper)">
  </param>
  <rosparam file="$(find franka_control)/config/franka_control_node.yaml" />
  