defining pyGDP Environment function

Adds a quick function to define the global URLs used in the pyGDPwebProcessing object, based on the environment you want to work in. Not user facing at the moment, though that can change.
@jiwalker-usgs , you are right. However, lets go ahead and put this in as is for now. We are going to do a whole-hog refactor of pyGDP soon. At that time, we'll pull these out into a config file of some sort.