Make volume_type updatable for cinder volume

[huangtianhua]

According to cinder retype action to make volume_type updatable for cinder volume in heat.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/137509

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/137509
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=9aafa787465e09cd5637656bfbae7f9f26784b2c
Submitter: Jenkins
Branch: master

commit 9aafa787465e09cd5637656bfbae7f9f26784b2c
Author: huangtianhua <email address hidden>
Date: Thu Nov 27 12:25:10 2014 +0800

    Support cinder volume retype

    Make volume_type updatable for cinder volume resource.
    Notes: this feature support in volume api v2, to raise
    NotSupported exception if the volume api version is v1
    for volume_type updation.

    Change-Id: I4b8b658a58ad0ef09763e99e9da8948cf72fed48
    Closes-Bug: #1395975