indicator.in (set-state): Make it work

* indicator/indicator.in (open-and-configure-device): Set `O_NONBLOCK'
  and `O_NDELAY' options for the port.
  (set-state): Open the port every time the procedure called, close it
  at the end.
  (open-server-socket): Reuse the address.
  (main): Store the path to the serial port device.