Cluster-tools

This release ensures that logging output which is done using pythons `logging` module is not swallowed by default. The cluster tools will set up the logging module with `logging.DEBUG` by default. You can override this by passing a `logging_config` argument to the constructor of the SlurmExecutor. The keys/values of that argument should correspond to the arguments which can be passed to `logging.basicConfig`.

get_executor` only accepts one positional argument now. All the others (which are passed to the actual executor subclass) should be name-based.

When using `map` on a slurm executor, slurm's job array feature is used.