minor fixing on environment setup

[fengggli]

Hi Daniel,
I got the chance to deploy Comanche to my workstation recently. I spent some time negotiating with the Department to get the full root access to it...
Some suggestions:

1. uuid-dev is required by spdk (/uuid/uuid.h)
2. the change in src/lib/core/CMakeLists.txt is for out-of-tree build
3. I also maintained a wiki on configuring qemu with nvme support with libvirt in my fork (https://github.com/fengggli/comanche/wiki/vm). Hope it's also useful for other collaborators.
   Thanks