Add static transform publisher (#51)

launch/panda_control_moveit_rviz.launch

 <?xml version="1.0" ?>
 <launch>
+  <!-- If needed, broadcast static tf for robot root -->
+  <node pkg="tf2_ros" type="static_transform_publisher" name="virtual_joint_broadcaster_1" args="0 0 0 0 0 0 world panda_link0" />
+
   <arg name="robot_ip" />
   <arg name="load_gripper" default="true" />
   <arg name="launch_rviz" default="true" />