v2.0 Release Candidate 0

This is a pre release for the upcoming v2.0 release.

The code base of nvme-cli has been splitted into a nvme-cli and libnvme. Also there were a lot's of cleanups and refactoring. Hence we decided to increase the major version number.

There are still a few things to sort out but nothing serious before the v2.0 release. So please give it a test and report any bug you find.

Thanks!