Set hostname in /etc/hosts on worker nodes

[chrisrichardson]

It seems that mpd might need to have this information set, at least for the node itself, e.g.

10.0.0.5     worker0

in /etc/hosts

[juhaj]

I doubt this is correct. The present version works just fine without that as long as you use srun instead of mpirun. Using srun is slurm's recommended way of launching MPI jobs anyway, so I doubt there's much reason to add the nodes into /etc/hosts, especially since they are present in DNS anyway.