Now works with Node 0.6.4

Since the version of Node shipped on Raspbian's distribution is 0.6.19, according to http://ricochen.wordpress.com/2012/07/24/install-node-js-on-raspberry-pi-in-two-simple-steps/ , it might be worthwhile to make the API work on older versions of NodeJS.

It's also important for me because I test on a Ubuntu 10.04 machine, which ships with Node 0.6.4.