bugfix clicking on diff image and dataURI
bugfix clicking on diff image and dataURI

Chrome no longer allows dataURIs to be viewed directly in the URL bar ([background](https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/GbVcuwg_QjM%5B101-125%5D)).

Currently clicking on the #image-diff element loads a blank page and gives an error:

> Not allowed to navigate top frame to data URL

This change opens the new window as `about:blank`, creates an image element, and appends that to the page.
Huddle/Resemble.js,Huddle/Resemble.js,kamilbielawski/Resemble.js,kamilbielawski/Resemble.js,rsmbl/Resemble.js,rsmbl/Resemble.js