Rename brunchcoffee to brunch.coffee

so that coffee-script's node monkey-patches take effect, particularly
for child_process.fork

https://github.com/jashkenas/coffee-script/blob/84b8b5cceef6c452996d022c4c2d47dc8c8a5ccc/src/coffee-script.coffee#L182-L192
Initial basic worker structure
Worker compilation proof of concept