nailgun 0.9.1 (zombie formula)

As per #21880 nailgun was removed because it was woefully outdated and had moved to a new packaging format. This commit brings the nailgun formula back from the boneyard and updates it to 0.9.1.

I've also taken a stab at writing a test, but there's a few ways that it's not ideal. Just testing the ng command would miss testing the server, but there's no good way that I can see to spin up the ng-server without backgrounding the process and waiting for it to bind to its port.

Also, if there's a way to get an unassigned port from the ephemeral range in Ruby, I'd rather do that than hard code 8765, but I didn't find a simple way to pick an unused port. 
In this case it's a stand-alone jar, yeah.

The alternative was to try and run the maven on the users' box, but the way maven works is that it goes out and fetches most of its code from central.maven.org (or different places, depending on the user's configuration). Since the end goal was to produce an identical duplicate of the `nailgun-jar`, this seemed easier.