Fix error message during simulation

[AndriyPt]

I execute

roslaunch leobot_launch simulation.launch

and get these errors

[Err] [InsertModelWidget.cc:302] Missing model.config for model "/home/user/workspace/leobot/base/src/leobot/leobot_gazebo/../.circleci"
[Err] [InsertModelWidget.cc:302] Missing model.config for model "/home/user/workspace/leobot/base/src/leobot/leobot_gazebo/../.git"
[Err] [InsertModelWidget.cc:302] Missing model.config for model "/home/user/workspace/leobot/base/src/leobot/leobot_gazebo/../.idea"
[Err] [InsertModelWidget.cc:302] Missing model.config for model "/home/user/workspace/leobot/base/src/leobot/leobot_gazebo/../docker"
[Err] [InsertModelWidget.cc:302] Missing model.config for model "/home/user/workspace/leobot/base/src/leobot/leobot_gazebo/../docs"
[Err] [InsertModelWidget.cc:302] Missing model.config for model "/home/user/workspace/leobot/base/src/leobot/leobot_gazebo/../leobot_2dnav"
[Err] [InsertModelWidget.cc:302] Missing model.config for model "/home/user/workspace/leobot/base/src/leobot/leobot_gazebo/../leobot_control"
[Err] [InsertModelWidget.cc:302] Missing model.config for model "/home/user/workspace/leobot/base/src/leobot/leobot_gazebo/../leobot_description"
[Err] [InsertModelWidget.cc:302] Missing model.config for model "/home/user/workspace/leobot/base/src/leobot/leobot_gazebo/../leobot_gazebo"
[Err] [InsertModelWidget.cc:302] Missing model.config for model "/home/user/workspace/leobot/base/src/leobot/leobot_gazebo/../leobot_launch"
[Err] [InsertModelWidget.cc:302] Missing model.config for model "/home/user/workspace/leobot/base/src/leobot/leobot_gazebo/../leobot_msgs"
[Err] [InsertModelWidget.cc:302] Missing model.config for model "/home/user/workspace/leobot/base/src/leobot/leobot_gazebo/../leobot_web_server"
[Err] [InsertModelWidget.cc:302] Missing model.config for model "/home/user/workspace/leobot/base/src/leobot/leobot_gazebo/../udev"

There should not be such errors in the log in the same level of logging.
Please check how models are loaded in other projects such as https://github.com/ROBOTIS-GIT/turtlebot3_simulations

[SystemDiagnosticss]

In this link KumarRobotics/mrsl_quadrotor#4 tell about this problem.
This problem is internal bugs of Gazebo 7.xx with gazebo_ros. We use 7.14 Gazebo version in docker container. If we downgrade our Gazebo to 7.0 the error will probably disappear.
Also that error can be considered as warning and we can ignore it.