First stab at adding ngrep

I'm not sure what to call the licence; it seems to be the BSD licence
with a few clauses about attribution added (which I *think* we're
complying with)

This has only been tested on Yosemite.

I'm guessing this will need some tweaking (the name of the license at least) before it can land.
Hello @jamezpolley , you can drop this `Description` file, it's no longer in use. But you can use a short description  on the top of Makefile, like `Description=ngrep provides a grep-like interface to the network layer`.