Merge "Pass environment variables of proxy to tox"

tox.ini

@@ -7,6 +7,7 @@ envlist = py26,py27,pep8
 usedevelop = True
 install_command = pip install {packages}
 setenv = VIRTUAL_ENV={envdir}
+passenv = http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY
 deps = -r{toxinidir}/test-requirements.txt
 commands =
     nosetests {posargs:fuel_plugin_builder}