Closes-Bug: 1379442

Previously, the glance-api start script would use the container
IP instead of the proxy IP for the public url when creating the
keystone endpoint. This causes keystone to provide an unreachable
IP within the public url and other OS services are unable to
connect to the public url.

Change-Id: I44befc84a90f59d535a951ee81aaff0fa1ba952d