Two 'Unsupported records' warnings when starting

[coreyhaines]

When staring up and loading the zones (from the example json), we get

2018-10-29 10:28:32.395 [warning] <0.155.0>@erldns_zone_parser:json_record_to_erlang:471 Unsupported record (data: [undefined,undefined,undefined,undefined,undefined])
2018-10-29 10:28:32.395 [warning] <0.155.0>@erldns_zone_parser:json_record_to_erlang:471 Unsupported record (data: [undefined,undefined,undefined,undefined,undefined])

warnings in the debug log.

If this is expected, it is potentially confusing for new people running this. Could be worth either removing these or determing which records they are and supporting them.