Update dependency links in NPM package

[myndzi]

The optional dependency in package.json pointing to https://github.com/godsflaw/nodeunit/tarball/master is no longer supported and causes npm installs to stall out horribly (and therefore possibly not run the rebuild script, which causes the module not to work at all)

This should be fixable simply by changing the url to https://github.com/godsflaw/nodeunit/archive/master.tar.gz

[godsflaw]

I fixed this earlier, are you seeing a new problem?

[myndzi]

Don't know what counts as earlier, but I just did a clean "npm install" and still received the same error

[godsflaw]

Ahh, I forgot to publish it to npm