[Part11] Remove six
[Part11] Remove six

We don't need this in a Python 3-only world.
Remove six in follows:
zaqar/storage/base.py

Change-Id: I5d589d9d74e747c55c4a6b7d5743785def57cc83

openstack/zaqar,openstack/zaqar,openstack/zaqar,openstack/zaqar