port tests out of nodeunit

[brodycj]

since there is no desire to support nodeunit in the future, see discussion in a PR that I had raised: caolan/nodeunit#356

I just saw tap2junit tool discussed in nodejs/admin#413, wonder if that tool could help us somehow?

[erisu]

Just pointing out that if we replace the existing unit testing framework for this repo, I think we would go with Jasmine. For consistency purposes, all of our other repos use Jasmine already. It would probably be a major task to migrate to Jasmine.

This is just a comment, not voting in favor of one or the other without a deeper investigation.