Instance_group object should have tighter attribute checking

[Dan Smith]

The instance_group object needs to use the dict and list helpers for its policies, metadetails, and members attributes. Right now they could have unserializable and heterogeneous values, which will break things. This is important to get in for Havana for schema correctness going forward.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/45304

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/45304
Committed: http://github.com/openstack/nova/commit/6bb8a3b0a7ed04acaa8dc53640adc5063841100b
Submitter: Jenkins
Branch: master

commit 6bb8a3b0a7ed04acaa8dc53640adc5063841100b
Author: Dan Smith <email address hidden>
Date: Thu Sep 12 13:41:25 2013 -0700

    Fix use of bare list/dict types in instance_group object

    The instance_group object was merged before we had helpers for
    dict and list objects of strings. This makes that object use those
    for schema safety.

    Change-Id: I1f68e43a83f140f7b29b17c0961b267e64e48390
    Closes-bug: 1221383