• Certain error codes reported by the ACME server that indicate a problem with the
  configured data now immediately switch to daily retries. For example: if the ACME
  server rejects a contact email or a domain name, frequent retries will most likely
  not solve the problem. But daily retries still make sense as there might be an
  error at the server and un-supervised certificate renewal is the goal. Refs #222.
• The max delay for retries has been raised to daily (this is like all retries jittered
  somewhat to avoid repeats at fixed time of day).
• No longer debug logging the ocsp renewal success with an error indicator. Fixes #197.
• When handling ACME authorization resources, the module no longer requires the server
  to return a "Location" header, as was necessary in ACMEv1. Fixes #216.
• Removed the "authz" subcommand from the a2md executable. This was a left over of ACMEv1.
• The module now reuses the internal curl instance in each MDs interaction
  with the ACME server. This means that open connections are reused.