Use Snakemake disk_mb resource to set HTCondor request_disk

[agitter]

Currently grid-submit.py checks whether the Snakemake mem_mb resource is set. If it is, that value is used to set the HTCondor request_memory attribute. The same can happen with disk by checking disk_mb and setting request_disk. This caused a problem for me when I tried using this profile to submit to a HTCondor queue that is configured to reject all jobs that do not set request_disk.