libvirt: Cleanup L2 and L3 rules when confirm vm resize
libvirt: Cleanup L2 and L3 rules when confirm vm resize

Cleanup security group and nwfilter rules on source node in
resize-confirm.

Add test cases for confirm_migration and _cleanup_resize.

Fixes bug 1050196

Change-Id: Id5495c41f3b51aa555a540f2c8aa718b653ae034

n0ano/ganttclient