Add download_url to setup()
Override bdist_egg command; don't add "missing" __init__.py

setuptool's bdist_egg "helpfully" adds "missing" __init__.py files to
declare namespaces for certain packages. This creates surprising
behavior when installing PEP 420 NS packages--other packages in the
namespace become unimportable.

I'm not sure if this also need to be added to every other tangled
package. Ugh.

Refs https://bitbucket.org/pypa/setuptools/issue/148