This is an initial, simple live migration test from one
running VM to another, using monitor commands.

This is also an example of using the new common.qemu functions
for controlling multiple running qemu instances, for tests that
need a live qemu vm.
Reviewed-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NJeff Cody <jcody@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>