flake8
passed.
JSHint
passed.
Add Python 3 version checks and classifiers for packaging.
Review Request #9739 — Created March 4, 2018 and submitted
The classifiers for Djblets 2.0 now lists Python 3.4/3.5/3.6 as
supported versions. It also prevents installation on 3.x versions prior
to 3.4.
Override
pyverwith different versions, checking that the package would
fail on those.
