In the early days of placement, the CORS middleware's config
options were registered out of band with other options, probably
due to efforts to use non-global config and avoid conflicts with
nova's use of the same settings. Now that placement always uses
non-global config, we can change setup back to something more
normal.
At the same time a gap in header-visibility defaults is corrected.
The updated test confirms header visibility. When the 'allow_headers'
configuration setting in fixtures/gabbits.py is removed, it fails.
Change-Id: I8481b3016de19e1617810cb3d3efa092560dfbb7
Chris Dent
fc35e3112e