remove -J from test-ci and fix test-net-dns-custom-lookup

This pulls in #1531 as well because it's the way to get passing builds on Jenkins when combined with removing -J from the test runner.

Ideally we should be able to use -J but it's borked on most of the build slaves but it would be nice if we could have it working so they are quicker to run. Something for @indutny to chime in on perhaps, @jbergstroem has also been looking at it.

Test run for these 2 commits: https://jenkins-iojs.nodesource.com/job/iojs+any-pr+multi/630/