Update changelog to reflect 0.19.0. (#5170)

CHANGELOG.md

@@ -2,6 +2,51 @@
 
 Certbot adheres to [Semantic Versioning](http://semver.org/).
 
+## 0.19.0 - 2017-10-04
+
+### Added
+
+* Certbot now has renewal hook directories where executable files can be placed
+  for Certbot to run with the renew subcommand. Pre-hooks, deploy-hooks, and
+  post-hooks can be specified in the renewal-hooks/pre, renewal-hooks/deploy,
+  and renewal-hooks/post directories respectively in Certbot's configuration
+  directory (which is /etc/letsencrypt by default). Certbot will automatically
+  create these directories when it is run if they do not already exist.
+* After revoking a certificate with the revoke subcommand, Certbot will offer
+  to delete the lineage associated with the certificate. When Certbot is run
+  with --non-interactive, it will automatically try to delete the associated
+  lineage.
+* 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.
+
+### Changed
+
+* 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. You can provide an additional directory for Certbot to
+  parse using the command line flag --apache-vhost-root.
+
+### Fixed
+
+* 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+  if certificates maintained by Certbot had been revoked has been fixed.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.
+
+More details about these changes can be found on our GitHub repo:
+https://github.com/certbot/certbot/milestone/43?closed=1
+
 ## 0.18.2 - 2017-09-20
 
 ### Fixed