(Adds final scores, quotes) By Liana B. Baker RIO DE JANEIRO, Aug 13 (Reuters) - Britain's Justin Rose has golf's first gold medal in 112 years in his sights after he edged ahead to take the lead in the Olympic tournament on Saturday. Rose got a blistering start by firing eagles on the third and fifth holes. "When you're looking at this situation, you're looking at the shiniest medal possible," Rose said. More...