Rebuild Hypervisor detection

[widhalmt]

Change to a more elegant way than lots of nested if's.

[widhalmt]

The problem is Xen's two line output, otherwise a simple case would be sufficient

[log1-c]

As there is no Hyper-V in the Hypervisor detection yet, here is what the output looks like (tested on Ubuntu 14.04 and 16.04

sudo virt-what
hyperv

If I am not mistaken the script part would look like:

elif [ "$(echo ${VIRT} | awk '{print $1}')" = "hyperv" ]
        then
          VIRTUAL=true
          HYPERVISOR="Hyper-V"