Fix test suite to use MiniDNS
Fix test suite to use MiniDNS

MiniDNS changes:

* In create_entry/delete_entry, if we don't get a name
then we throw an exception

* In get_entries_by_address, filter out duplicates

* Add a log.warn in addition to throwing an exception.

Test Suite changes:

* Updates base TestCase to use MiniDNS instead of the default DNSDriver.

* Make sure we cleanup the dnstest.txt and the temporary directory
  in TestCase.tearDown()

* Update a few tests to pass in display_name

Fixes LP Bug #1081750

Change-Id: Ia8d80102deaeaaac166ab50bbd47279d72d1e389

openstack/oslo.versionedobjects,citrix-openstack-build/oslo.versionedobjects