nagios: Remove nagios leftovers
nagios: Remove nagios leftovers

Nagios isn't maintained nor used and got partly replaced my SOCM. So
let's drop the dead code.

Follow-up for crowbar/crowbar-openstack#1586

crowbar/crowbar,rsalevsky/crowbar,dirkmueller/crowbar,rsalevsky/crowbar,aplanas/crowbar,crowbar/crowbar,aplanas/crowbar,dirkmueller/crowbar