Add setup.py for packaging

[sbellem]

This pull requests proposes to add a setup.py that will allow the packaging of honeybadgerbft so that it can be more easily installed and also published (e.g.: on PyPI).

This way one could eventually install the package using:

$ pip install honeybadgerbft

It may be observed that various development and testing libraries are included. These are suggested libraries that can ease the development and testing phases. They will not be installed when running:

$ python setup.py install

However, the "extra" libraries may be installed like so:

# dev extras
$ pip install -e .[dev]

# test extras
$ pip install -e .[test]

# docs extras
$ pip install -e .[docs]

[sbellem]

Commit 03562cf was merged via #29