Page loading extensions.

Great DSL for Phantom.js really helped with refactoring a Node.js scraper I'm working on.

For a Javascript heavy site I was looking to interact with the UI, I noticed the page would hang forever. I found there to be a discrepancy in the resource counter when onLoadFinished was fired. So I've added a flag to only wait for AJAX resources after the page is ready.

In addition I used the loading status to automatically wait for AJAX to load after mouse click when the page is being interacted with.

This is my first pull request btw :ghost: