Releasing steps

• Run python3 setup.py nosetests, python2 setup.py nosetests
• Update version number in setup.py and CHANGES.rst
• git commit -m "Preparing ${VERSION}" setup.py CHANGES.rst
• git tag -as ${VERSION}
• make init all
• python3 setup.py sdist
• twine upload --sign dist/isso-${VERSION}.tar.gz