WIP Piper node mode

This doesn't handle sample-level job tracking yet w.r.t the database and also I need to add a Charon update into the sbatch file before checking the coverage to see if we can proceed with sample analysis, but the rest of it seems to work. I'm aware that parts of it are a little hacky (#fix later) but I'm open to suggestions for improvements as well.
Yeah it looks kind of horrible because I'm writing a bash conditiional in Python. I can't really think of another way to launch the analysis from an sbatch script though because it is in fact bash and I need to test the condition then (and not now, while I'm writing the sbatch file). Maybe @guillermo-carrasco has another idea?