coffee-script as a devDependency + prepublish

Hi,

as it's suggested in the npm documentation ( https://npmjs.org/doc/scripts.html ), it would be nice if coffee-script wasn't mandatory with the npm release. Same thing for mocha.

Also, I see you're using a Makefile. I'm not very opinionated about that, but theses tasks could as well be put in the package.json's scripts section.

What do you think ? I would send a pull request if you're ok with that.

Do you have plan to release the coffe-script version soon ?
I have a feature I would like to suggest and implement directly in the coffe-script version.