Enable migration without shared storage from the monitor

Enable migration without shared storage from the monitor

This patch adds the option to activate non-shared storage migration from the
monitor.
The migration command is as follows:
(qemu) migrate -d tcp:0:4444 # for ordinary live migration
(qemu) migrate -d -b tcp:0:4444 # for live migration with complete storage copy
(qemu) migrate -d -i tcp:0:4444 # for live migration with incremental storage copy, storage is cow based.

Changes from v4:
- Minor coding style issues.

Signed-off-by: Liran Schour <lirans@il.ibm.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>