linux-nvme user space tooling update

[Keith Busch]

I've gotten really good feedback and contributions on the linux nvme
command line interface I started up. Since it's getting some traction,
I thought it best to further open this, so moved to a github project:

   https://github.com/linux-nvme/nvme-cli

Please feel free to join in if you're interested.

Anyone more familiar with writing command line utilities may spot some
questionable tactics, like hard-coded install paths. It's a work in
progress. :)