Fix merge problem with risk_assess_fls branch

[albertohata]

There was a merge problem with the risk_assess_fls branch (c77b940).

Some files were removed and should be added again:

• simulation-ros/src/turtlebot2i/turtlebot2i_safety/CMakeLists.txt
• simulation-ros/src/turtlebot2i/turtlebot2i_safety/msg/SafetyZone.msg
• simulation-ros/src/turtlebot2i/turtlebot2i_safety/package.xml

[Andrew Berezovskyi]

Closing as wontfix; the project is finished and the repository is to be archived.