Add an Option to inject pagedjs polyfill

[mutschler]

While paged.js works well when it's directly included in the head tag of the Site when it's added via script injection ($browser->setOption('addScriptTag', '{"url": "https://unpkg.com/pagedjs/dist/paged.polyfill.js"}')) there need to be done some evaluation a wait for a specific selector is added.

Im not sure about the option setter, it might be better to support the json syntax from above so one could include a local path version of pagedjs as well. For our case using the remote one is fine, but i could change that if you'd prefer the other variant :)