Re-implement Distribution as OS

It now uses /etc/os-release instead of lsb_release, like the cool kids
are doing.

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>
Skip hostname test

Due to the workaround put in place recently

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>