Add prince 9.0r4

Prince PDF converter.

This was recommended to be moved to homebrew/binary in the discussion [here](https://github.com/Homebrew/homebrew/pull/25907), which the original author hasn't done in 2 weeks.  In there was also a question about the license which is [here](http://www.princexml.com/license/), though I'm not sure if I'm supposed to do anything about that.