Replace magic value 'service/security' in CADF notifications

[Steve Martinelli]

In the _send_audit_notification method of the CadfNotificationWrapper class, there in magic value used at line 290, https://github.com/openstack/keystone/blob/master/keystone/notifications.py#L290

observer=resource.Resource(typeURI='service/security'))

In the latest release of pycadf, a constant was created, so we may now use that value.

pyCADF change:
https://github.com/openstack/pycadf/commit/f7fc5ac01252347e050b3516be94933c31d28af9

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/95550

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/95550
Committed: https://git.openstack.org/cgit/openstack/keystone/commit/?id=017cdf2595623fc648e48170635503861eaf717f
Submitter: Jenkins
Branch: master

commit 017cdf2595623fc648e48170635503861eaf717f
Author: Steve Martinelli <email address hidden>
Date: Mon May 26 11:32:29 2014 -0400

    Replace magic value 'service/security' in CadfNotificationWrapper

    With the 0.4.1 version of pycadf released, we can remove the use
    of a magic value in the _send_audit_notification function

    Change-Id: I5b8c33e8867a65eda242a83601e1f58b85c98112
    Closes-Bug: #1323341