Include which resolver IP was used in the JSON output

[nmalcolm]

Please describe your feature request:

Include which resolver IP was used in the JSON output

Describe the use case of this feature:

Sometimes resolvers misbehave and we end up with invalid subdomains. It would help a lot if we could log which IP resolved the subdomain so we can remove it from our resolvers file.

[GeorginaReeder]

Thanks for this @nmalcolm , we'll take a look into it :)