Python 3.6 support

Fix/py36 (#20)

* fix: add py36 to build plans

* fix: adjust to changes in setuptools

* fix: try again

* fix: stubborn setuptools..

* fix: different way to get versions

* try again

* ..and again

Python 3.6 support

Fix/py36 (#20)

* fix: add py36 to build plans

* fix: adjust to changes in setuptools

* fix: try again

* fix: stubborn setuptools..

* fix: different way to get versions

* try again

* ..and again