Uses the clientutil.Backend abstraction for the keystore client API.

It left the Prometheus instrumentation in server/http.go, while
it is already provided by the ai3/go-common package.

Panic on short reads and other errors.

Uses 'go generate' to invoke sri.py.

Which would be the GeoLite2-Country.mmdb one.

This enables correct (hopefully) support for IPv6 lookups. Also add
support for the special "onion" zone for Tor Hidden Services.

Classic mistake with strings.Split("").

Otherwise gopkg.in/yaml.v2 won't decode strings to []bytes.

The proxy wraps endpoints (exposed as separate HTTP hosts) with single-sign-on
authentication.