python-fuelclient: use environment variables in tox.ini

[Vladimir Kozhukalov]

Due to tox issue [1] we removed all the cases where we used environment variables like {env:VAR:DEFAULT}. Now the issue is fixed and we can revert the patch. We need it to be possible to define tox behavior via environment to solve the issue [2]

[1] https://bitbucket.org/hpk42/tox/issues/285/tox-220-breaks-some-toxini-config-files
[2] https://bugs.launchpad.net/fuel/+bug/1517408

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/260419

[Fuel Devops McRobotson (fuel-devops-robot)]

Related fix proposed to branch: master
Change author: Roman Prykhodchenko <email address hidden>
Review: https://review.fuel-infra.org/14903

[Fuel Devops McRobotson (fuel-devops-robot)]

Reviewed: https://review.fuel-infra.org/14903
Submitter: Dmitry Kaigarodsev <email address hidden>
Branch: master

Commit: 0243869d2f31e59d46fb6e301f3eb53db0be677b
Author: Roman Prykhodchenko <email address hidden>
Date: Tue Dec 29 10:11:29 2015

Use tox>=2.3.1 for python-fuelclient

Tox has to be upgraded in order to not hit the bug [1] with
self-reverencing parameters.

1. https://bitbucket.org/hpk42/tox/issues/285/tox-220-breaks-some-toxini-config-files

Related-bug: #1528494
Change-Id: I3251ff80bf088980c552edf16ff1d395eb7b9414

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/260419
Committed: https://git.openstack.org/cgit/openstack/python-fuelclient/commit/?id=407c3f79cd066e485cd667ad511a4f0137bde1ec
Submitter: Jenkins
Branch: master

commit 407c3f79cd066e485cd667ad511a4f0137bde1ec
Author: Roman Prykhodchenko <email address hidden>
Date: Tue Dec 22 10:42:25 2015 +0100

    Revert "Don't set environment variables in tox.ini"

    This reverts commit 3e7738fd3fb18a2d5f53b1ecc9706dc53b65a511 and a minor
    temporary change in base functional test made in
    07e5fb8cbed222252caa74b32953fa162053ac9d.

    Since tox-2.3.1 was released, all the abovementioned changes are not
    needed anymore.

    Closes-bug: #1528494
    Change-Id: I23d3cd4c7fa31e58a4f173a1cc15c4b54f794f43