When requesting a certificate for a subdomain, the DNS record was
attached to the domain instead.
E.g.
Requested:
ww1.example.com
Created:
_acme-challenge.example.com
instead of
_acme-challenge.ww1.example.com
I also had to rename the `envAuth()` in the Cloudflare implementation
to avoid the "redeclared" error
acme/dns_challenge_dnsimple.go:41: envAuth redeclared in this block
previous declaration at acme/dns_challenge_cloudflare.go:154
