Add Pixstor API script for calculating total quota use

Added new gpfs-python-api directory for scripts using the Pixstor Python API. This essentially wraps the mmapplypolicy command and introduces a couple of new tools like the MapReduce rule. Typical GPFS policies cannot perform any form of aggregation on a file list leaving that to be done in a post-processing script. The MapReduce rule lets us do that aggregation without needing to save and parse what could be an extremely long list. The only downside for this is that any nodes running the rule need to have access to the API, so just the NGenea nodes for now.