We include a list of DUTs in the dut-pool-inventory email for DUTs that haven't run any jobs in the last 24 hours.

This list is currently quite long (today's list had 97 DUTs). We can't expect the deputy to realistically look at that many DUTs.

Let's
- Include a column with #of days since last job (so we know how unused a DUT has been)
- Sort decreasing by this column.

That way, the deputy can prioritize the first few, if needed.

Currently, the list is sorted in a way that DUTs of the same pool / board show up together. Since that will no longer be the case, it's probably necessary to include the 
- top (2?) boards with # of idle DUTs
- top (2?) pool with # of idle DUTs
so that any board / pool systemic problem jumps out at us.