Feature request: Implement printer vendor APIs

[vswarte]

Hi there!

First off I wanted to say: thanks for writing this library, it has been a major timesaver.
I'm in the process of doing some hobby projects and I was wondering if the library could be adapted to also allow PHP software to be registered as a printer. Thus, fetching jobs like a real printer.

I see the API documentation is available right here: https://developers.google.com/cloud-print/docs/proxyinterfaces
The structure of the API look rather similair to what your library is communicating with right now.

Thanks,
Vincent Swarte.

[nilov]

Thanks, the link of documentation I add in README.