Deprecate domains

ref https://github.com/iojs/io.js/issues/66

Also, I did notice that domain.dispose() is deprecated but missing a deprecation message. So it includes a commit which fixes it. Please inform me if you want it as a separate pull request.

I've also changed two test assertions. I belive usage of domain in lib/repl.js was swallowing the assert errors and that those are currently broken.