Add python-defusedxml as new dependency
Add python-defusedxml as new dependency

It has been added as dependency for cinder in [1].

[1] https://review.openstack.org/#/c/528516/

Change-Id: I0568e1686bb4c3f83594f835ba6d93ac7e3e822b

redhat-openstack/rdoinfo,javierpena/rdoinfo