Comment 88 for bug 1640978

Did some major cleanup of this bug. Debdiffs attached for review.

In general, the primary change for the backport was to modify the package to build against Python 2 instead of Python 3; one code change was needed in certbot to disable API documentation as the necessary sphinx module is not available. We're still sorting out the letsencrypt compat shims but I wanted to get these debdiffs reviewed as they are final or very close to.