* acmeserver: support specifying the allowed challenge types
* add caddyfile adapt tests
* acmeserver: add `policy` field to define allow/deny rules
* allow `omitempty` to work
* add caddyfile support for `policy`
* remove "uri domain" policy
* fmt the files
* add docs
* do not support `CommonName`; the field is deprecated
* r/DNSDomains/Domains/g
* Caddyfile docs
* add tests
* move `Policy` to top of file
Mohammed Al Sahaf