Add support for z.ps

Add support for [z.ps](https://github.com/JannesMeyer/z.ps)

I included z as a submodule so any upstream updates would be pulled in. I'm not sure how scoop deals with submodules, so this approach may not work. I don't know how to test scoop locally to confirm, but this code is working fine with my local copy of pshazz.

Reference https://github.com/lukesampson/scoop/issues/59