Respond to notifies and allow a secondary to follow the SOA parameters
to update a zone from a primary. Also sprinkle it with logging.
Also extend monitoring to include qtype in more metrics.
Fix some file/secondary issues when parsing a Corefile, also allow
for multiple origins to be specified. Also don't fail on startup when
a zonetransfer fails.
Fixes: #54
Allow specifying a primary server and retrieve the zone's content.
Add tests and an Expired bool to zone struct, to stop server zones
that are expired. The zone is retrieved on Startup, no updates of
changed content are done. We also don't respond to notifies yet.
