Bug/214

Bug fix for issue #214
What about using the `$!` shell variable, which returns the PID of the last executed process? The idea is to include within the `${CYGNUS_COMMAND}` a way of saving that `$!` in a file. Something like this, maybe (not tested):

```
su ${CYGNUS_USER} -c "${CYGNUS_COMMAND} ; echo $! > ${CYGNUS_PID_FILE}"
```