rados-gw is incompatible with swift

Registering a keystone endpoint for rados-gw confuses Glance into using
rados-gw as object storage backend even when Swift is selected as Glance
backend (see also PRD-2012, PRD-2013).

This change drops objects_swift option from release.json and sets
objects_ceph in the setup wizard based on the Glance storage backend
selection made for images_ceph. Settings tab sets the images_ceph
checkbox when objects_ceph is set, and unsets objects_ceph when
images_ceph is unset.

Change-Id: I2764b0924a3888b44047513afe59ea08612bcb2e
Merge "rados-gw is incompatible with swift"