'Initialize an Open MapQuest geocoder with location-specific
address information, no API Key is needed by the Nominatim based
platform.
``format_string`` is a string containing \'%s\' where the string to
geocode should be interpolated before querying the geocoder.
For example: \'%s, Mountain View, CA\'. The default is just \'%s\'.'

def __init__(self, api_key='', format_string='%s'):

    self.api_key = api_key
    self.format_string = format_string
    self.url = 'http://open.mapquestapi.com/nominatim/v1/search?format=json&%s'
