DATAMONGO-1062 - Fix failing test in ServerAddressPropertyEditorUnitTests.

The test rejectsAddressConfigWithoutASingleParsableServerAddress fails because the supposedly non-existing hostname "bar" "now" resolves to a real host-address.

The addresses "gugu.nonexistant.example.org, gaga.nonexistant.example.org" shouldn't be resolvable TM.

Original pull request: #229.