Fix DNS SRV issues due to update to Go 1.11

[matheusd]

see golang/go#27546
and https://groups.google.com/forum/#!topic/golang-nuts/vAbjprJNPV0

At least one user in ubuntu 18.04 hasn't been able to use v0.6.2 due to that update to Go's DNS library.

[matheusd]

Won't fix for the moment (only add better error handling) since this is fixed in systemd-resolve.

Relevant PR is: systemd/systemd#9828

In the mean time, the only solution for ubuntu users is to skip service discovery via SRV record and manually configure the address of the target service (eg: MacherHost: split-ticket-svc.stake.decredbrasil.com).