Revert "Pass environment variables of proxy to tox"
Revert "Pass environment variables of proxy to tox"

It looks like you can work around this problem by setting an 
environment variable on your dev system. See 
https://tox.readthedocs.org/en/latest/config.html#confval-passenv=SPACE-SEPARATED-GLOBNAMES

This reverts commit b9ca1d534456aecfd4fd5caac053d4b1b49e231d.

Change-Id: Ib051f0a9f1b4277548c9473bfaed5db7b1bb18e1

openstack/python-magnumclient