BZ #1168755 - rabbitmq fix node names

https://bugzilla.redhat.com/show_bug.cgi?id=1168755

Explicitly use node names from the param
$lb_backend_server_names .  Otherwise, a mismatch can occur
and the rabbit cluster may not be formed.
Merge pull request #414 from cwolferh/bz1168755_rabbitmq_fix

BZ #1168755 - rabbitmq fix node names