Add config for performance gate job
Add config for performance gate job

This rally scenario is intended to be run in OpenStack CI
by rally-dsvm-neutron-neutron job.

Implements: blueprint neutron-performance-gate-jobs
Closes-Bug: #1334434
Change-Id: If204f3dfc32933792d09fdc929c248fc3f17b0bc

dougwig/x-neutron-fwaas,openstack/neutron-fwaas,openstack/neutron-fwaas,gaolichuang/neutron-fwaas,gaolichuang/neutron-fwaas,citrix-openstack-build/neutron-fwaas