Autolayout as WebWorker

Decoupled `klayjs`: the main operations are now at its [own module](https://github.com/automata/klay-js/blob/master/klay.js). Just `the-graph.html` refers to `klayjs`. Its interface is basically `init` and `layout`, both accepts parameters that are passed to the WebWorker running KlayGWT. It is not dependent of NoFlo graphs, so it works with any KGraph as well.

I already tested it with `noflo-ui` and it works on both Firefox, Chrome and as a Chrome Packaged App. I'm just waiting this PR be accepted to push to `noflo-ui` too. I'd like to test it on `the-graph` before get it on `noflo-ui`.