Updated openstack/openstack
Project: openstack/glance  43a08e0a41993303b176adc5145458b566dd4d5e
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Glance all: Replace basestring by six for python3 compatability

The builtin basestring abstract type was removed in python3,
use str instead, we need to using six.string_types to replace
the basestring for py3 compatibility.

Change-Id: Icf709b3499ff7f1ea935045153eb9a5ecb4618ee