Switch to using os-brick

This patch changes the internals of some
of the libvirt volume drivers to use the
os-brick Connector objects.   Cinder already
uses os-brick for volume discovery and removal
for copy volume to image and image to volume
operations.

This patch changes the following libvirt volume drivers:
LibvirtISCSIVolumeDriver
LibvirtISERVolumeDriver
LibvirtAOEVolumeDriver
LibvirtFibreChannelVolumeDriver

This patch also removes the need to have the
nova/storage module that was used by the above listed
libvirt volume drivers.

This patch also fetches the initiator side information
from os-brick.  This replaces the internals of the
libvirt driver's get_volume_connector

Also updated the rootwrap filters to consolidate them under
a single comment, and added a new os-brick needed command.

blueprint use-os-brick-library

Change-Id: I400db60fcc29c2d5e2d3b9dabc055649138468eb
Depends-On: Id36f9665c8ff2a720713ceaaa5b05f9b03706681

requirements.txt

@@ -51,3 +51,4 @@ oslo.middleware>=2.4.0 # Apache-2.0
 psutil<2.0.0,>=1.1.1
 oslo.versionedobjects!=0.5.0,>=0.3.0
 alembic>=0.7.2
+os-brick>=0.3.2 # Apache-2.0