Add healthcheck middleware to pipelines

[OpenStack Infra]

https://review.openstack.org/387731
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commit eeac2cb6d1bdb7b5330cf24b1d98151876e9f672
Author: Jesse Keating <email address hidden>
Date: Mon Oct 17 17:20:54 2016 -0700

    Add healthcheck middleware to pipelines

    This introduces the oslo healt check middleware
    http://docs.openstack.org/developer/oslo.middleware/healthcheck_plugins.html
    into the pipelines. This middleware is useful for load balancers and
    http servers, which can use it to validate that the keystone services are
    operational. This middleware is being used in other services such as
    glance and magnum. This patch provides it for keystone, in an effort to
    spread the usage across all major projects.

    This is one less item that operators will have to patch locally.

    DocImpact

    Change-Id: I19e4fc8f6c6a227068ba7191c1e9c453fc08f061

[Steve Martinelli (stevemar)]

I asked jesse what he wanted documented, I'm not sure what he wants added, we added release notes and developer docs. I'm not sure it's necessary to add this to the admin guide, since no other middlewares are documented there.

[Launchpad Janitor (janitor)]

[Expired for OpenStack Identity (keystone) because there has been no activity for 60 days.]