policy.json missing "volume_extension:services:update" rule

[Anna Sortland]

The update API in cinder/api/contrib/services.py extension is trying to check authorization:
        authorize(context, action='update')
but corresponding rule is missing in sample /etc/cinder/policy.json:
   "volume_extension:services:update": "rule:admin_api"
We should add it.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/201776
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=68ec9d7b7fb5fcd8b1e80e0121c8079d69f8fb4d
Submitter: Jenkins
Branch: master

commit 68ec9d7b7fb5fcd8b1e80e0121c8079d69f8fb4d
Author: Anna Sortland <email address hidden>
Date: Tue Jul 14 14:51:51 2015 -0500

    Update authorization actions for services API

    Previously, the services extension used generic authorization check
    "volume_extension:services" for both index and update APIs.

    This change creates separate rules for index and update APIs
    so that it is possible to assign different rules to different users.
    The sample /etc/cinder/policy.json is also updated to include new rules:
        "volume_extension:services:index": "",
        "volume_extension:services:update" : "rule:admin_api"

    Change-Id: Ib57171f5011210861478590bbdfc30cce25e62b4
    Closes-Bug: #1471995
    Closes-Bug: #1471999