log-based test for load/apply config

log-based test for load/apply config

Add a new system test which checks named output when starting,
reconfiguring and reloading the server. It checks that the steps where
configuration is loaded, when named enters exclusive mode, and when the
configuration is applied are all logged, and that they occur in the
correct order. This adds a guard/warning to keep the parsing of the
named.conf outside of the exclusive mode.