lemonbar: Breakout condition logic to Shelf class

.i3/lemonbar/i3_lemonbar_launcher.py

@@ -210,7 +210,7 @@ if __name__ == "__main__":
     common.health_logger = logging.getLogger('Health logger')
     common.health_logger.addHandler(handler)
 
-#    common.logger.basicConfig(stream=sys.stdout, level=debuglvl)
+    # Make sure no other instance running and ensure clean up on exit
     assert_only_instance() # Creates pid file and fifo file
     atexit.register(clean_up)
     signal.signal(signal.SIGTERM, handle_exit)