cpus-per-task as required for slurm

[erikenbody]

Working on a slurm cluster that does not allow the cpus-per-task command prevented me from running the workflow. I just commented out the bits of slurm_utils.py that have this cpus-per-task and it worked fine. Suggest that we have cpus-per-task as a configurable option in the yaml rather than hard coded, but I am not sure how to best approach this. See this branch edits as an example of what solved my issue [uppmax branch(https://github.com/harvardinformatics/snpArcher/commit/24b3831a11bc3ed6968d4e6f18a068e9e2618351)

[erikenbody]

@tsackton I have been reviewing this issue (#148) and seems like this code that I commented out in this issue may no longer be needed. Can we remove cpus-per-task from slurm-utils safely? with the --slurm flag is it safe to just set this in the profile itself, rather than as a default option here. It would certainly make this more flexible to other slurm systems

[tsackton]

Probably we need to rethink the entire profile setup here. We shouldn't actually be distributing a cluster-specific profile with snpArcher; we should instead point people to https://github.com/Snakemake-Profiles/doc or similar. I am trying to read more about this and figure out the best options - will hopefully test a bit locally this week.

[cademirch]

Fixed in #170