Test register appliance nondestructive

RHSM still failing randomly - looking into it (well it's not actually failing - the test however is)

yaml for testing https://url.corp.redhat.com/8795662

py.test -k register_appliance

Update:
Ok, I just ran it 5 times in a row and it didn't fail so I'd say merge it if you're happy with it and I'll keep an eye out for this one on jenkins.