Be more explicit in the logs when a notify fails.
New notify error message looks like:
2016/11/07 18:21:42 [ERROR] Notify for zone "example.org." was not accepted by "8.8.8.8:53": rcode was "SERVFAIL"
Correctly pick up secondaries
When multiple secondary are specified make sure they are picked up.
Fixes#393#398
Add auto-load middleware that automatically picks up zones.
Every X seconds it will scan for new zones.
Add tests and documentation.
Make 'make test' use -race.