CoffeeScript is a devDependency, not a runtime dependency

Hello, you don't need to `require "coffeescript"` in each file to use coffeescript. Leaving it there affects other coffeescript files because you're using an out of date version, so if I use your library and then want to `require("foo.coffee")` elsewhere in the project, then it will use your older version, leading to really, really strange bugs.

This PR fixes the issue.