Removed costmap_2d/msg/OccupancyGridUpdate.msg and pointed to map_msgs instead.
changed from costmap_2d/OccupancyGridUpdate to map_msgs/OccupancyGridUpdate in enhanced_nav_display
Merge pull request #80 from ros-planning/use-map-msgs

Use OccupancyGridUpdate message from map_msgs package now that it's been released.