Using chrome headless in spiderable

I started to experiment with chrome-headless in spiderable, because i could not manage to get phantomjs running anymore. Details here: https://github.com/meteor/meteor/issues/8661

i started a simple fork of spiderable and managed to get it running with chrome with good results, but it needs some work to start and stop processes in a reliable way.

So if anyone is interested in this, please write :slight_smile: