rootfs: stop monit and snmpd before restart

stop explicitly snmpd before reboot to avoid messages:
Jan  1 00:54:23 snmpd[1290]: read_config_store open failure on /var/lib/snmp/snmpd.conf
Otherwise snmpd was stopped after unmount of filesystems.

Stop monit to avoid possible respawn of processes during shutting down.

remove "null" from the line in /etc/inittab
null::shutdown:/etc/init.d/rcK
to get printouts to the console.

Signed-off-by: Adam Wujek <adam.wujek@cern.ch>