Proposal: remove pygeoprocessing as a dependency

[davemfish]

We're using a few convenient pygeoprocessing functions right now,

pygeoprocessing.get_gis_type
pygeoprocessing.get_vector_info
pygeoprocessing.get_raster_info

Each are called one time. It's convenient to have them, but perhaps not worth including the whole of pygeoprocessing as a dependency. We could replace these by using the GDAL API directly. It might result in some code being basically duplicated in geometamaker and pygeoprocessing. We miss out on beneficial updates to these functions in pygeoprocessing, but we get the benefit of potentially customizing them to the needs of geometamaker without needing upstream changes.

See also #46