Some Image attributes defined in openstacksdk are named differently
from actual properties managed by Glance. Because openstackclient
checked property names to be unset against Image object properties,
it was impossible to unset such properties.
This patch introduces a IMAGE_ATTRIBUTES_CUSTOM_NAMES dictionary
mapping real property names with custom attribute names.
Closes-bug: #2115732
Change-Id: I7296fc293dff9208464c9a07f58ce3e9ffabd3e9
Signed-off-by: Alexey Stupnikov <aleksey.stupnikov@gmail.com>