libvirt.tests: Add testcases for migrating with virtio-scsi devices.

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>
libvirt.tests: Append lost disk format.

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>
libvirt.tests: Amendments for migration with virtio-scsi device.

 * For some machine, dns does not work properly, it may
   takes very long time to login.So allow more time for logging.
 * Fix the codes for creating ssh-autologin.

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>
libvirt.tests: Add parameter to set multifunction on.

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>
Merge pull request #311 from yumingfei/scsi_migration

libvirt.tests: Add testcases for migrating with virtio-scsi devices.