Update security/py-{acme,certbot} to 0.20.0.

0.20.0 - 2017-12-06

- Certbot's ACME library now recognizes URL fields in challenge
  objects in preparation for Let's Encrypt's new ACME endpoint.
- The Apache plugin now parses some distro specific Apache
  configuration files on non-Debian systems allowing it to get a
  clearer picture on the running configuration.
- Certbot better reports network failures by removing information
  about connection retries from the error output.
- An unnecessary question when using Certbot's webroot plugin
  interactively has been removed.
- Certbot's NGINX plugin no longer sometimes incorrectly reports that
  it was unable to deploy a HTTP->HTTPS redirect when requesting
  Certbot to enable a redirect for multiple domains.
- Problems where the Apache plugin was failing to find directives and
  duplicating existing directives on openSUSE have been resolved.
- An issue running the test shipped with Certbot and some our DNS
  plugins with older versions of mock have been resolved.
- On some systems, users reported strangely interleaved output
  depending on when stdout and stderr were flushed.

0.19.0 - 2017-10-04

- Certbot now has renewal hook directories where executable files can
  be placed for Certbot to run with the renew subcommand.
- After revoking a certificate with the revoke subcommand, Certbot
  will offer to delete the lineage associated with the certificate.
- When using Certbot's Google Cloud DNS plugin on Google Compute
  Engine, you no longer have to provide a credential file to Certbot
  if you have configured sufficient permissions for the instance which
  Certbot can automatically obtain using Google's metadata service.
- When deleting certificates interactively using the delete
  subcommand, Certbot will now allow you to select multiple lineages
  to be deleted at once.
- Certbot's Apache plugin no longer always parses Apache's
  sites-available on Debian based systems and instead only parses
  virtual hosts included in your Apache configuration.
- The plugins subcommand can now be run without root access.
- certbot-auto now includes a timeout when updating itself so it no
  longer hangs indefinitely when it is unable to connect to the
  external server.
- An issue where Certbot's Apache plugin would sometimes fail to
  deploy a certificate on Debian based systems if mod_ssl wasn't
  already enabled has been resolved.
- A bug in our Docker image where the certificates subcommand could
  not report if certificates maintained by Certbot had been revoked
  has been fixed.
- Certbot's RFC 2136 DNS plugin (for use with software like BIND) now
  properly performs DNS challenges when the domain being verified
  contains a CNAME record.


(fhajny)