Remove unused variable 'image_member_factory'

Fixes LP: #1134465

Change-Id: I99b7f4754646a93f2f6625c50f99585dd8b381ba
Switch to oslo.config.

The oslo-config package has been renamed. Switch to the new
version. (should fix SmokeStack).

Change-Id: I6744337008825498a2f0f5c74139661410968f50
Merge "Switch to oslo.config."
Merge "Remove unused variable 'image_member_factory'"