Switch maintainers to Open Robotics.

Also update the authors to include the people from Robotis
who did the work to update here.

Signed-off-by: Chris Lalancette <clalancette@openrobotics.org>

package.xml

@@ -23,16 +23,17 @@
     and mapping (SLAM) in 2D and 3D across multiple platforms and sensor
     configurations.
   </description>
-  <maintainer email="cartographer-owners@googlegroups.com">
-    The Cartographer Authors
-  </maintainer>
+  <maintainer email="clalancette@openrobotics.org">Chris Lalancette</maintainer>
+  <maintainer email="michael@openrobotics.org">Michael Carroll</maintainer>
   <license>Apache 2.0</license>
 
   <url>https://github.com/googlecartographer/cartographer</url>
 
   <author email="google-cartographer@googlegroups.com">
     The Cartographer Authors
   </author>
+  <author email="thlim@robotis.com">Darby Lim</author>
+  <author email="pyo@robotis.com">Pyo</author>
 
   <buildtool_depend>catkin</buildtool_depend>