message: updated test_two_kinects_one_map.launch to use single map frame
diff: <arg name="device_id" value="#2" />
  </include>
  - <node pkg="tf" type="static_transform_publisher" name="world_to_map1"
  - args="0 0 0 0 0 0 world map1 100" />
  - <node pkg="tf" type="static_transform_publisher" name="world_to_map2"
  - args="0 0 0 0 0 0 world map2 100" />
  -
  <include file="$(find rtabmap_ros)/launch/rtabmap.launch">
  <arg name="namespace" value="rtabmap1"/>
  <arg name="localization" value="true" />
  <arg name="frame_id" value="camera1_link" />
  - <arg name="map_frame_id" value="map1" />
  <arg name="vo_frame_id" value="odom1" />
  <arg name="rgb_topic" value="/camera1/rgb/image_rect_color" />
  <arg name="namespace" value="rtabmap2"/>
  <arg name="localization" value="true" />
  <arg name="frame_id" value="camera2_link" />
  - <arg name="map_frame_id" value="map2" />
  <arg name="vo_frame_id" value="odom2" />
  <arg name="rgb_topic" value="/camera2/rgb/image_rect_color" />
  