Support multiple pools in VNX Cinder driver

[Tina Tang]

This is a enhancment to VNX Cinder driver. Priviously, the VNX driver only support managing a single storage pool or all the pools on a VNX system. This change aims to let the VNX cinder driver manages a set of storage pools(not all) on the VNX system.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/184001

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/184001
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=2b04acc3ccc4c827f17e351b1a38b068cf11eb9a
Submitter: Jenkins
Branch: master

commit 2b04acc3ccc4c827f17e351b1a38b068cf11eb9a
Author: Tina <email address hidden>
Date: Sun May 17 21:12:10 2015 -0400

    Multiple pools support enhancement in VNX cinder driver

    This introduced a new option "storage_vnx_pool_names" which
    replaced the existing option "storage_vnx_pool_name". The new option
    allows user specify more than one pools to be managed by a vnx
    cinder back end.

    DocImpact
    This change will introduce a new configuration option, so that the
    documentation need to be updated.

    Change-Id: Id6c3a1ecb32484fbd35dbb5814262103b322249e
    Closes-Bug: 1456062