Added MX lookup tests.  Added code to tests to validate answer resource record types rather than just counts.
Added MX lookup tests.  Added code to tests to validate answer resource record types rather than just counts.

tonistiigi/dnsdock,kgutwin/dnsdock,ConZ27/dnsdock,mpeters/dnsdock,ps2/dnsdock,jverdeyen-forks/dnsdock,dougmarcey/dnsdock