message: added merging of joint_states to hw launch
diff: <launch>
  <arg name="robot_ip" default="localhost" />
  <arg name="arm_id" default="franka_emika" />
  + <arg name="load_gripper" default="false" />
  <node name="$(arg arm_id)" pkg="franka_hw" type="franka_hw_node" output="screen" required="true">
  <rosparam command="load" file="$(find franka_hw)/config/franka_hw.yaml" />
  <rosparam command="load" file="$(find franka_hw)/config/default_controllers.yaml" />
  <node name="state_controller_spawner" pkg="controller_manager" type="spawner" respawn="false" output="screen" args="franka_state_controller --shutdown-timeout 2"/>
  <node name="robot_state_publisher" pkg="robot_state_publisher" type="robot_state_publisher" output="screen"/>
  +
  + <group if="$(arg load_gripper)">
  + <node name="joint_state_publisher" type="joint_state_publisher" pkg="joint_state_publisher" output="screen">
  + <param name="robot_description" command="$(find xacro)/xacro --inorder '$(find franka_description)/robots/FEA_01_01_Gripper.urdf.xacro'" />
  + <rosparam param="source_list">[franka_state_controller/joint_states, franka_gripper_node/joint_states]</rosparam>
  + </node>
  + </group>
  + <group unless="$(arg load_gripper)">
  + <node name="joint_state_publisher" type="joint_state_publisher" pkg="joint_state_publisher" output="screen">
  + <param name="robot_description" command="$(find xacro)/xacro --inorder '$(find franka_description)/robots/FEA_01_01.urdf.xacro'" />
  + <rosparam param="source_list">[franka_state_controller/joint_states]</rosparam>
  + </node>
  + </group>
  </group>
  </launch>
  