....I..... [RSM-1] add support for new SLV values calculation

This includes creating items when executing tld.pl and adding values
to Zabbix at a runtime:
  - DNS downtime
  - DNS NS downtime
  - DNS number of probes that returned results
  - DNS number of probes that returned positive results
  - DNS required positive results by SLA
  - RDDS downtime
  - EPP downtime