Pin to pre-zookeeper version of nodepool
Pin to pre-zookeeper version of nodepool

The nodepool devs are about to merge zookeeper bits into master in
preparation of future zuulv3 work. We don't want to be on that bleeding
edge yet, so pin to the latest tag as suggested by the nodepool release
email[1].

[1] http://lists.openstack.org/pipermail/openstack-infra/2016-December/004972.html

jamielennox/hoist,jamielennox/hoist,SpamapS/hoist,BonnyCI/hoist,BonnyCI/hoist,SpamapS/hoist