`hostname` output should be equal to `hostname -f`

[vrutkovs]

kubelet uses node hostname as node name since 3.10 - and it has to be a FQDN name, otherwise ansible would wait for wrong pods to be created (task Wait for control plane pods to appear never finishes).

It seems this repo doesn't configure cloudprovider, so it should be safe to do:

hostnamectl set-hostname $(hostname -f)

on every host before install. WDYT?