Event Stream v3.3.6 has a vulnerability and conflicts with `npm install` execution

[Flyerfye]

Running npm install && bower install && npm start as per the development section in your README results in the issue described here: https://stackoverflow.com/questions/53578201/npm-err-404-not-found-event-stream3-3-6 You might consider changing the specified version to 3.3.5 or 4.0.1 instead

https://github.com/evansque/polygonize/blob/1946cbed351e0217f5faf365dea2479d1d3c7346/yarn.lock#L1132