rodi_ws_node: execute top-level code only if running in main scope
rodi_ws_node: execute top-level code only if running in main scope

A module can discover if is running in the main scope by checking whether
its __name__ scope equals to __main__. The rodi_ws_node.py script is not
supposed to be imported but still is a good practice to add this check.

benjayah/rodi_robot,rodibot/rosdi_ws,rodibot/rodi_robot