Tolerate images created with other means
Tolerate images created with other means

when image was created by other means (or older openstacksdk)
the `openstack.image.v2.image.Image["properties"]` may be present but be
`None`.

When such image is present and one tries to create another image with
the same name but different content, current openstacksdk fails with

AttributeError: 'NoneType' object has no attribute 'get'

Change-Id: Ia8a88587d74d3a4081c8f9e23099e3da2077820e
Story: 2007898
Task: 40287

stackforge/python-openstacksdk,stackforge/python-openstacksdk