sdist on PyPI doesn't contain pulp_cli fake module

[evgeni]

#283 introduced a fake, non-namespaced module called pulp_cli which is needed to make old setuptools happy. sadly, this is only added to the distributed source when the tarball is built using such an old setuptools, which is usually not the case.

this results in the following error when trying to install from such an sdist:

error: package directory 'pulp_cli' does not exist