Fixes #582 - adds Google Maps API key

Fixes #582 - adds the ability to set a Google Maps api key when loading
the Google Maps APIs. If no API key is set the maps APIs load
anonymously from google.
Please add an empty line at the end of the file. That red circle with the arrow that shows up in the diff here and also in GitHub for Mac lets you know that the file is missing a newline at the end. If you hover over that red icon here, it will say "No newline at end of file".