Log Message:
Update py-certbot and py-acme to 0.14.0.
Use ALTERNATIVES to handle different Python versions better.

0.14.0 - 2017-05-04

Added

- Python 3.3+ support for all Certbot packages. certbot-auto still
  currently only supports Python 2, but the acme, certbot,
  certbot-apache, and certbot-nginx packages on PyPI now fully support
  Python 2.6, 2.7, and 3.3+.
- Certbot's Apache plugin now handles multiple virtual hosts per file.
- Lockfiles to prevent multiple versions of Certbot running
  simultaneously.

Changed

- When converting an HTTP virtual host to HTTPS in Apache, Certbot
  only copies the virtual host rather than the entire contents of the
  file it's contained in.
- The Nginx plugin now includes SSL/TLS directives in a separate file
  located in Certbot's configuration directory rather than copying the
  contents of the file into every modified server block.

Fixed

- Ensure logging is configured before parts of Certbot attempt to log
  any messages.
- Support for the --quiet flag in certbot-auto.
- Reverted a change made in a previous release to make the acme and
  certbot packages always depend on argparse. This dependency is
  conditional again on the user's Python version.
- Small bugs in the Nginx plugin such as properly handling empty
  server blocks and setting server_names_hash_bucket_size during
  challenges.