fix position of safety box in gazebo. doc must be written/updated!

src/SafetyAwarePlanner.cpp

@@ -63,6 +63,7 @@ int main(int argc, char** argv)
     std::vector<moveit_msgs::CollisionObject> collision_objects = sec.createCentralizedSafetyEnvironment(move_group);
 
     // show safety box in gazebo
+    safety_box_pose.position.z += .5 * safety_box.BOX_Z;
     GazeboZoneSpawner::spawnCollisionBox(safety_box, safety_box_pose);
 
     //visual_tools.processCollisionObjectMsg(collision_objects[2], rviz_visual_tools::RED);