Update neutron options for icehouse

Also fixed up some duplicate config options due to a bug in autohelp.py.
While working through duplication options, I believe I encountered some
that weren't being output, but I'd rather spend the time fixing the tool
than manually adding those.

Change-Id: I60eb035b97d354bc57168421facafd895ace2a10
Add CORS mention to object storage sec of confref

CORS was a feature added in Grizzly. This simple patch adds a new
section to the config reference, detailing what it is and the single
configuration option so far.

Change-Id: Ied2d5615e7b666370bc6d0dff136d305ba8cee62
Closes-Bug: 1107326
Merge "Add CORS mention to object storage sec of confref"
Merge "Update neutron options for icehouse"