autotailor generates xml with NS0 namespace

[johanmontald-cloud]

The generated tailoring file has namespace ns0, which is inconsistent with the SSG file where the prefix for NS = "http://checklists.nist.gov/xccdf/1.2" is xccdf-1.2.
To rectify, modify autotailor with

31a32

NS_PREFIX = "xccdf-1.2"
267a269,271
#--- Set the NameSpace Prefix, otherwise ns0 is used.
ET.register_namespace(NS_PREFIX, NS)

[Mab879]

Issued created #2309.