- new constant Client::VALIDATION_DNS
- added Authorization::getDnsChallenge to get the challenge
- added Authorization::getTxtRecord to get the TXT record value
- added Helper::waitForDNS to provide an easy way to wait for changes
- updated documentation to illustrate DNS validation
According to https://tools.ietf.org/html/rfc8555#section-7.1.4 the
status of an authorization object can only be "pending", "valid", or
"revoked".
An order can have a status of "ready" but never an authorization.