add etherpad-lite process monitoring via NRPE, RT #5790

- since change 86253 nagios-nrpe-server is running and nagios-plugins available
- nrpe_local.cfg.erb = local command that runs on the node
- checkcommands.cfg.erb = command that runs on the monitoring host
- then use monitor_service in puppet class

Change-Id: Ida3dd6c1861412cbab1e45e833d5a7fe7191a51b
Merge "add etherpad-lite process monitoring via NRPE, RT #5790" into production