Missing KOLLA_TAG variable

Change-Id: Ic97841cb9d27a9fc5cb7967f3da1b2f016988d20
Closes-bug: #1469332

Implements the neutron-openvswitch-agent plugin container.

Co-Authored-By: Sam Yaple <sam@yaple.net>
Partially Implements blueprint: openvswitch-container

Change-Id: Ie0fa318541e16d730b7007d3620c7873e898ed4a