Write release procedure

[twm]

As a follow-up to #67, write up a release procedure that describes the steps to release Afkak and publish it to GitHub releases and PyPI.

[twm]

Here's a draft:

Release Procedure

1. Update version in setup.py and afkak/__init__.py.

2. Update the changelog with the new version number. Review the release notes, editing and reformatting as necessary.

3. Make sure tests still pass (tox etc.).

4. Tag release

   version="$(python setup.py --version)"
   git tag $version
   git push origin $version
   

5. Generate release artifacts:

   tox -e twine -- python setup.py sdist --formats=gztar
   tox -e twine -- pip wheel -w dist/ --no-deps dist/afkak-${version}.tar.gz
   tox -e twine -- twine check dist/afkak-${version}.tar.gz dist/afkak-${version}-py2.py3-none-any.whl
   

6. Generate a GitHub release from the tag:

   python -m webbrowser "https://github.com/ciena/afkak/releases/tag/${version}"
   

   Update the tag to contain the release notes from CHANGES.md.

7. Upload to PyPI:

   tox -e twine -- twine upload dist/afkak-${version}.tar.gz dist/afkak-${version}-py2.py3-none-any.whl
   

8. Visit https://pypi.org/project/afkak/ and make sure everything looks okay.