Bumped calver

Bumped calver to this year and month.

Attached source tarball and wheel to release.

Updated developer dependencies, relaxed python version

Works with Python 3.6 officially now.
Did work before as well but was not officially supported by the package.

Updated dependencies for developers in the pip-files (not used for the PyPI package).

Updated twine/requests

This only changes the local development environment for library developers.
No change for library users.

Changed setup-script

Setup-scripts now runs find_packages(…) by default

Public Release

This is the first public release of safemd, a safety first focused markdown renderer for python.