Parse XML results to JSON files

after running XCCDF or OVAL scans, parses results.xml file to
results.json one in the format acceptable by our `worp` API.

vendored-in is `untangle` lib v1.1.0
(https://github.com/stchris/untangle, MIT License)

Change-Id: I87f106c4b8b678e1b125ffab832f80ee261a4781
Related-Issue: https://mirantis.jira.com/browse/PROD-23159
Related-Issue: https://mirantis.jira.com/browse/PROD-23160
3 files changed