Specify how many CPUs each compute node has. This is useful when using
a `SelectType` different from `select/linear`, because otherwise SLURM
will not be able to automatically discover the amount of CPUs
(cfr. https://computing.llnl.gov/linux/slurm/faq.html#fast_schedule)
Install slurmdbd on a SLURM cluster and configure basic Priority.
Fixes issue #3