added an example world file utilising the new box obstacle
added an example world file utilising the new box obstacle

BCLab-UNM/SwarmBaseCode-ROS,BCLab-UNM/SwarmBaseCode-ROS,BCLab-UNM/SwarmBaseCode-ROS,BCLab-UNM/SwarmBaseCode-ROS,BCLab-UNM/SwarmBaseCode-ROS,BCLab-UNM/SwarmBaseCode-ROS