Users can supply a compset and resolution to subset non-default files in subset_data.py

Right now we use default forcing data (i.e. surface, land use, DATM) to subset, and currently we only support use on Cheyenne.

In the future users should be able to supply a compset and resolution (there will be default values if not supplied) which the script will use to find the location of the correct surface, land use, and/or DATM data to subset.

This will potentially make the current config file no longer necessary - but we may still want users to be able to optionally supply a config file for data (e.g. DATM data - GLDAS for example) that is not currently associated with a compset.