Creating a source distribution so we can easily install this via Pip. We need to do this until we get our changes into the upstream or the upstream supports netmask.

Steps to create release:

• Checkout repo on branch you want to release. This was created from ns1 branch.
• Edit the setup.cfg file, commenting out the sdist alias. We do this because we don't want to build the docs as well as the source tarball.
• In the top-level project folder do: python setup.py sdist. This will create the release tarball ./dist.
• Attach that tarball to this release tag.
• Done.