Create a background process to run Guetzli

[mikeschinkel]

Guetzli is a Google tool that can create “high quality JPEG images with file sizes 35 percent smaller than currently available methods.”

The reason is would be a great addition to WPLib Box is because "Guetzli takes 'significantly longer' to compress images than other methods of JPEG encoding" and as such it would be a great background process that could be configured by options in project.json.

Later the box could even possibly be used to optimize imagines at the hosting account by pulling them down via HTTP and then uploading the compressed versions via STFP.