WASHINGTON — Cuba’s blue, red and white-starred flag was hoisted today at the country’s embassy in Washington in a symbolic move signaling the start of a new post-Cold War era in U.S.-Cuba relations.Cuban Foreign Minister Bruno Rodriguez presided over the flag-raising ceremony hours after full diplomatic relations with the United States were restored at the stroke of midnight, when an agreement to resume normal ties on July 20 took effect. Earlier, without ceremony, the Cuban flag was hung in the lobby of the State …