Trapping Ctrl+C handler didn't work.

It made Windows Service Controller pause for a while to give processes a
graceful opportunity to exit, then presumably it timed out and killed
all the processes anyway.
Added a command to run 'restart' from another process group.

This allows the service to restart itself.
If we use the regular "restart" command, Windows Service Control
Manager will make sure to kill the entire process group (including
the "winsw.exe restart" itself), preventing the service from getting
restarted.