[Openstack-stable-maint] Proposing Morgan Fainberg for stable maintenance

tl;dr I consider it an oversight that Morgan is not already on the stable maintenance team. Morgan has a demonstrated interest in (and ability to contribute towards) maintaining backwards compatibility, security and stability. I'd certainly trust his votes on stable/* branches. I don't think I need to say much more! stable/icehouse reviews: https://review.openstack.org/#/q/reviewer:%22Morgan+Fainberg+%253Cmorgan.fai... stable/havana reviews: https://review.openstack.org/#/q/reviewer:%22Morgan+Fainberg+%253Cmorgan.fai... stable/grizzly reviews: https://review.openstack.org/#/q/reviewer:%22Morgan+Fainberg+%253Cmorgan.fai... -Dolph