Provide monitor naming of xen disks, and plumb guest driver
notification through xenstore of resizing instigated via the
monitor.
[BR: minor edits to pass qemu's checkpatch script]
[BR: significant rework needed due to upstream xen disk qdevification]
[BR: At this point, monitor_add_blk call is all we need to add!]
Signed-off-by: Bruce Rogers <brogers@suse.com>