libvirt-svirt: Add test for VM starting and destroying in svirt.

Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
Add test for save and restore in svirt

Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
libvirt_vm: fix save_to_file and restore_from_file method.

Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>