No longer whitelist externally-hosted requirements

* pypi_mirror/cmd/run_mirror.py: Stop whitelisting netifaces,
psutil, pysendfile and pytidylib for insecure/external hosting
off-PyPI. They all now host versions on PyPI which meet the listed
requirements in openstack/requirements:global-requirements.txt for
currently supported branches.

Change-Id: I640a85435de7bb300aaaa347cb97b1fad7543e17
Merge "No longer whitelist externally-hosted requirements"