memcached: implement leader election
memcached: implement leader election

Change-Id: I82bfdce0174410f7cb15bf594fa4c6a364881df1
Co-Authored-By: Sahid Ferdjaoui <f799991784850b8d4b84e1fdbe797720df9aae1a@cloudwatt.com>

openstack/tooz,citrix-openstack-build/tooz,openstack/tooz,citrix-openstack-build/tooz