When The Library of Congress established a Prize for Popular Song in 2007, one name was affixed to it: Gershwin. With no disrespect to Messrs. Berlin, Porter, Rodgers and company, George and Ira’s surname is synonymous with the gold standard in American popular song. The recipients of the award to date – Paul Simon, Stevie Wonder, Paul McCartney, Burt Bacharach and Hal David, Carole King and Billy Joel – have all followed in the Gershwins’ footsteps of marrying smart, sophisticated and incisive lyrics to unabashedly melodic, sweeping musical statements. Starbucks’ recent compilation…