Pypoolparty

- new feature: `pool.starmap()`
- longer cool down times for SLURM

Bug fixes in SLURM --array.
Better debugging for SLURM --array,
no more numpy in here, it was overkill

New slurm.array.Pool to use SLURM's --array option.
Also, explore the use of zip-files to reduce the number of files in the work_dir.
Further, improving tests by making sure jobs actually go into error states.

Now less likely for crazy environment variables to break the worker_node.py script.

better naming. better docstrings. more better ;)