[jsk_pcl_ros] support including tabletop_object_detector.launch file in any name space

[MiyabiTane]

Using this launch file, you can write as follows

<launch>
  <group ns="hoge">
    <include file="$(find jsk_pcl_ros)/sample/tabletop_object_detector.launch">
      <arg name="input" value="/extract_indices/output" />
      ...
    </include >
  </group>
</launch>