Update MapQuest lookup for new mandatory API key requirement
Update README to reflect new MapQuest API requirements & configuration
Update unit tests for new MapQuest API key configuration settings
Merge pull request #486 from robdiciuccio/mapquest

API key required for MapQuest Open services.

As of 15 July 2013. See: http://developer.mapquest.com/web/products/open/forums/-/message_boards/view_message/459709