py35 tempest job

[YAMAMOTO Takashi]

make it work and have a job.
it's one of a pike goal.
not a hard requirement for neutron subprojects right now.

https://governance.openstack.org/tc/goals/pike/index.html
https://etherpad.openstack.org/p/ptg-pike-python35
https://etherpad.openstack.org/p/neutron-ptg-pike-final

[Antonio Ojea (aojea)]

https://review.openstack.org/490447

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.openstack.org/490484

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/490484
Committed: https://git.openstack.org/cgit/openstack/networking-midonet/commit/?id=bcb338f8b30eee144edbd21be5e54e9d80f7549f
Submitter: Jenkins
Branch: master

commit bcb338f8b30eee144edbd21be5e54e9d80f7549f
Author: Antonio Ojea <email address hidden>
Date: Thu Aug 3 15:45:03 2017 +0200

    Enable python3 support in devstack

    We need to be able to choose between version v2 and v3 of python when we
    run devstack.
    This patchs adds a new variable to the gate-hook.sh script that permits
    to pass a parameter to select the python version used in devstack gates.

    gate_hook.sh <midonet-plugin> <python version>

    For backwards compatibility with previous jenkins jobs if the python
    version is ommitted it uses python2, if it receives "-py35" it will
    use this version.

    Related-Bug: #1670255

    Change-Id: If0a0ddffb1323e76ca9dc151d12f57e692d5dae5
    Signed-off-by: Antonio Ojea <email address hidden>