auth_url is missing when switching to stored context

[Qiming Teng]

When creating new servers as a result of receiving an alarm to an autoscaling group, we switch to the store context.
Since the updated stack is using the stored context, the context will propagate into servers created.

'auth_url' was missing from the stored context so when refreshing the 'os-collect-config.conf' file, auth_url is gone.
The result is that newly create server cannot signal back to Heat.

Need to add 'auth_url' into the stored context and possibly 'region_name' if not harmful.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/151216
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=1a3adcdcb13c661a5ef3e5551172249b20006bc0
Submitter: Jenkins
Branch: master

commit 1a3adcdcb13c661a5ef3e5551172249b20006bc0
Author: Steven Hardy <email address hidden>
Date: Thu Jan 29 12:59:37 2015 +0000

    Store auth_url and region_name when trusts are enabled

    We don't currently store auth_url, which causes problems when creating
    autoscaling groups containing servers configured for software config,
    because we use context.auth_url to populate the auth_url in the server
    metadata, which is needed by the deployments for signalling.

    Also adding region_name, as this seems likely to be needed for correct
    operation in a multi-region environment.

    Closes-Bug: #1415901
    Change-Id: I550d03ea1b6985ba0777bf5ca52c79a8e8e60f5a