 Copy the RHEL6 eventlet workaround from Oslo
 Copy the RHEL6 eventlet workaround from Oslo

Tests in oslo-incubator now need the horrendous hack to workaround an
issue with eventlet on RHEL6. We've moved the patch_tox_venv tool
and redhat-eventlet.patch into oslo-incubator, so add them to
openstack-common.conf.

Change-Id: I1acfec282b64d7582144b155119bedb1741db2f7

Tehsmash/networking-cisco,cisco-openstack/networking-cisco,CiscoSystems/networking-cisco,Tehsmash/networking-cisco-apic,noironetworks/networking-cisco,Gitweijie/first_project,noironetworks/networking-cisco,openstack/networking-cisco,hareeshpc/networking-cisco,nikolay-fedotov/networking-cisco,hareeshpc/networking-cisco,Gitweijie/first_project,CiscoSystems/networking-cisco,Tehsmash/networking-cisco-nexus,openstack/networking-cisco,Tehsmash/networking-cisco,cisco-openstack/networking-cisco