New York Times: KAREN Denaro and Rebekah Marshall were lost. The two friends had finished poking through the shops and restaurants at Blue Back Square one recent Saturday and wanted to check out the retail on another street, LaSalle Road. But they had no idea where it was, and with temperatures climbing past 80 degrees, the search for it was quickly becoming a passing thought. Then David St. Germain cycled over in a yellow rickshaw and offered them a ride. Within minutes they were where they wanted to …