Add a minimum redis version check while starting
Add a minimum redis version check while starting

To avoid having the redis driver connecting to a
very old redis we should try to be defensive and
raise an exception if we are connecting to a redis
version that will just not provide enough working
functionality for this driver to work correctly.

Change-Id: Ic16990805d8ac015f2c1f12f44e4115dba366135

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