Workaround in case raw fastqs are gone and new contrasts are needed.

[tovahmarkowitz]

Goal: to make it possible to run new contrasts without using the chrom-seek run command (so as to avoid needing the raw fastqs)

Plan: Have a script that takes in the current config.json, a new peakcall file, and a new contrast file and produce an updated config.json so that a user can just run the kickoff script without involving the chrom-seek run command