Improve configuration for general use

[nicolepaul]

This code was initially set up to take inputs from the Global Risk Model, which has certain file name conventions and standards. To make this code public, I've refactored it a bit to allow for more general use. However, there are still some aspects of the code that could be improved to make the configuration clearer/easier for users.

For example, the code takes in an input of the country name but the _config.py file also has a country name specified in order to allow flexibility in the shapefile name.