Initial patch for BitWrk support (see http://bitwrk.net)

Hi,

I branched off from your repository in order to integrate the Go version of your raytracer with BitWrk, a peer-to-peer cloud computing service I am building.

This is meant to be a test implementation and tries to serve a learning purpose rather than be of actual use. Having a minimal input file, medium-sized output and high computation power requirements makes rays almost ideal as a BitWrk sample application.

As your stated goal is to perform language comparisons, you're probably not interested in this kind of integration. Still, if you like to, I offer you to merge my branch.

Cheers,
Jonas