The ZoneDataLoader can still be simplified to remove the vectors
in it (as the RdataSet now merges for us). This will be done
in a future commit.

* In some tests, the RdataSet list sequence changed (as there's no
  order enforced for this data). Tests were adjusted for it.
* Some test data was adjusted to add missing NS records.
* Some tests now pass and don't throw exceptions as duplicate
  records for a type are now accepted.