NVMe detection

[Shou]

This should reliably fix the /dev/nvme vs /dev/sda issue #20.

[jeaye]

Thank you for this! What sort of setup do you have which is use /dev/nvme? I'd like to test this locally, before merging, but I'm interested in the use case.

[Shou]

I've got a Dell XPS 13 which comes with a nice NVMe SSD drive and I know a few other ultrabooks to do the same, other than customized desktops or servers with NVMe drives that is.

The format should be the NVMe character device /dev/nvme0 followed by the namespace block device /dev/nvme0n1 and finally the partition /dev/nvme0n1p2, for example.

[jeaye]

Thank you!