Locality support for replication

[OpenStack Infra]

https://review.openstack.org/300669
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commit 187725fafb3952cf17b5109acb06a414a39790e2
Author: Peter Stachowski <email address hidden>
Date: Fri Apr 1 21:25:12 2016 +0000

    Locality support for replication

    In order to allow replication sets to be all on the same hypervisor
    (affinity) or all on different hypervisors (anti-affinity) a new
    argument (locality) needed to be added to the Trove create API.

    This changeset addresses the Trove server part of this feature.
    'locality' can now be added to the ReST payload for a create command
    and it is passed along as a scheduler hint to Nova.

    The replication scenario tests were enhanced to test that 'affinity'
    works and 'anti-affinity' fails (since devstack sets up a single
    hypervisor by default). A check for the existance (and
    lack of) server-groups was added. This is to ensure that not only is
    the server-group created properly, but also that it has been deleted
    after all the related instances are gone.

    DocImpact: New functionality

    Partially implements: blueprint replication-cluster-locality
    Depends-On: I18f242983775526a7f1e2644302ebdc0dac025cf
    Change-Id: I7d924c25d832f9ff4386e9497bfd214f1b2b3503