Rebase python-etcd3gw to 0.2.5 in train/el7 testing
Rebase python-etcd3gw to 0.2.5 in train/el7 testing

Includes some required python3 compat fixes.

Change-Id: I3513667545576ae9fbb0e7fdf5e1798c327daccf
Resolves: rhbz#1804445

redhat-openstack/rdoinfo