autotest/virt-test — pull request #1055 by Hao-Liu (2013-11-11 17:50:11+00:00)
Title: libvirt-test: Backup virsh_change_media xml and fix virsh_edit.

Added backup and restore for vm in virsh_change_media.py.
Fix virsh_edit.py to get consistent result in earlier version of libvirt.
Fix some errors.
Fix some pep8/pylint.