Create a Haystack index.  See:
            http://www.mongodb.org/display/DOCS/Geospatial+Haystack+Indexing

            :param name: Name of the indexed column
            :param bucket_size: Size of the haystack buckets (see mongo docs)

def geo_haystack(self, name, bucket_size):
        """ Create a Haystack index.  See:
            http://www.mongodb.org/display/DOCS/Geospatial+Haystack+Indexing

            :param name: Name of the indexed column
            :param bucket_size: Size of the haystack buckets (see mongo docs)
        """
        self.components.append((name, 'geoHaystack'))
        self.__bucket_size = bucket_size
        return self