Estimate memory usage

[mflynn-lanl]

Assembly workflows can fail due to insufficient memory requested. One solution is to increase the amount of memory requested in the runtime attribute to accommodate all samples. However, memory usage by the assembly workflow can vary depending on the sample. Requesting a lot of memory means some jobs will request more than is needed and so fewer jobs can run at the same time. Brian Foster has a python script that can estimate memory usage based on the sample. We will add this to our Assembly workflow to adjust memory requested to better reflect how much is needed.