etcd: Conditionally start/stop etcd server
etcd: Conditionally start/stop etcd server

Make sure to check if the df-etcd-server service is enabled before we
try and start or stop the etcd server.

Change-Id: Iaef3f5cf96f7c2bd888b725823f45311a19d7414
Signed-off-by: Kyle Mestery <9cfbda34e625c7b0454bcb19a48d07c46f9097d2@mestery.com>

openstack/dragonflow,FrankDuan/df_code,openstack/dragonflow,FrankDuan/df_code,FrankDuan/df_code,openstack/dragonflow