Merge pull request sensepost#2 from leonjza/master

Migrate to Go Modules and internal serialiser updates

Use agent mode by default.

Add googlefront provider.

This provider fronts dns.google.com with www.google.com.

Add Quad9 as supported DoH provider.

Update README.

Ignore certificate errors.

This is especially needed in cases where intercepting proxies may
be a thing on corporate networks.

Initial commit. 💥