record whether host is gadi or raijin

[aekiss]

Need to record whether host is gadi or raijin, i.e. $HOSTNAME

Not immediately obvious how to do this. There's no sign of "gadi" or "scratch" in the .yaml so we'll have to do more file parsing.

[aekiss]

having any input from /short in config.yaml should indicate a run on raijin

[aekiss]

host is also recorded as PBS_O_HOST in env.yaml; see #21