Add "cleanup" for created recordsets + NEW delete zone test

Test: "test_delete_zone_with_existing_recordset"
   1) Create a Zone
   2) Create a Recordset
   3) Delete a Zone
   4) Ensure successful deletion of Zone
   5) Ensure successful deletion of Recordset

Change-Id: I933a0cfd51554dfe25f43f4b5c52da97db4b8452
3 files changed