Handle test runner making requests to tracking endpoint

[sahava]

Some way to block requests to any given endpoint (e.g. google-analytics.com).

Alternatively, use URL parameter to make blocking easier via e.g. GTM.

[snipebin]

I forked this repo and I'm trying to accomplish this by swapping PhantomJS for https://github.com/GoogleChrome/puppeteer

Here's the resoaning behind that push:

1. Launch of headless chromium, with two prominent PhatomJS projects PhantomCSS and PhantomXHR having been deprecated as headless chromium is regarded as a better alternative.
2. Puppeteer provides an API for request interception and abort

Let me know your thoughts.