WEST PALM BEACH, Florida (Reuters) - Democrat Barack Obama will leave the presidential campaign trail to visit his ailing 85-year-old grandmother in Hawaii, whose health has deteriorated in recent weeks, an aide said on Monday. With two weeks left in an intense battle for the White House, Obama will hold a campaign event in Indianapolis on Thursday and then fly to Hawaii to see his grandmother before returning to campaigning on Saturday, aide Robert Gibbs said. "Senator Obama's grandmother, Madelyn Dunham, has always been one of the most important people in his life," Gibbs said in a statement. "Along with...