Print number of each pi before shutting it down
Print number of each pi before shutting it down

When I ran the script this morning,
3 of 12 shutdown commands failed in the first round.
Messages may help the user understand/remember
how the script works,
but could also fail,
because I have not yet actually tested
this updated version of the script!

jshoyer/raspi-topdown-plant-imaging-12x