Backport changes from Cinder to Nova-Volume
Backport changes from Cinder to Nova-Volume

NetApp C-mode driver.
Generic NFS-based block device driver.
NetApp NFS-based block device driver.

blueprint netapp-volume-driver-cmode
blueprint nfs-files-as-virtual-block-devices
blueprint netapp-nfs-cinder-driver
bug 1037619
bug 1037622

Change-Id: I513c3f88bcb03f3b71a453f92f5912d7730a8bbc

openstack/oslo.versionedobjects,citrix-openstack-build/oslo.versionedobjects