Use standard "service" command to control afdsmgrd

Currently, afdsmgrd is started via a custom script. Using its own startup script which allows to control it using the standard `service` and `chkconfig` tools, *e.g.*:

**Start it automatically at boot:**

    chkconfig --add afdsmgrd
    chkconfig afdsmgrd on

**Start and stop it:**

    service afdsmgrd start
    service afdsmgrd stop

The last two commands also work as unprivileged user (if `service` is not in the `$PATH`, `/sbin/service` should be used).