[Certbot-dev] Certbot 0.18.0

[Brad Warren]

Certbot 0.18.0 has been released. The changelog for the release is:

### Added

* The Nginx plugin now configures Nginx to use 2048-bit Diffie-Hellman
parameters. Java 6 clients do not support Diffie-Hellman parameters
larger than 1024 bits, so if you need to support these clients you will
need to manually modify your Nginx configuration after using the Nginx
installer.

### Changed

* certbot-auto now installs Certbot in directories under `/opt/eff.org`.
If you had an existing installation from certbot-auto, a symlink is
created to the new directory. You can configure certbot-auto to use a
different path by setting the environment variable VENV_PATH.
* The Nginx plugin can now be selected in Certbot's interactive output.
* Output verbosity of renewal failures when running with `--quiet` has
been reduced.
* The default revocation reason shown in Certbot help output now is a
human readable string instead of a numerical code.
* Plugin selection is now included in normal terminal output.

### Fixed

* A newer version of ConfigArgParse is now installed when using
certbot-auto causing values set to false in a Certbot INI configuration
file to be handled intuitively. Setting a boolean command line flag to
false is equivalent to not including it in the configuration file at all.
* New naming conventions preventing certbot-auto from installing OS
dependencies on Fedora 26 have been resolved.

More details about these changes can be found on our GitHub repo:
https://github.com/certbot/certbot/milestone/42?closed=1