Just a few notes about the work in progress and the expectations:
I think "make develop" should no longer create a virtualenv => developer should create manually, using virtualenv or virtualenvwrapper or no virtualenv at all... depending on developer preferences.
I'd like tox to run the tests
dependencies in etc/ci-requirements.txt may be completely moved to some tox file
some parts of the Makefile may be moved to tox configuration file
Refs #74.