Create a Shapefile interface for region specificaiton #6

A shapefile is a GIS file format that can represent a number of geographical shapes including counties, states/provinces, states, etc. I'm unfamiliar with shapefiles. Cartopy has shapefile support as well as NCL. While it appears that some shapefiles contain more then one region, they might be a nice way to specify an MPAS region.

Good places to start are:

• https://en.wikipedia.org/wiki/Shapefile
• https://github.com/GeospatialPython/pyshp
• https://github.com/Toblerity/Fiona