* Spieth earns accolade in vote of his peers * Banner season exceeds his own expectations (Adds detail, quotes, byline) By Mark Lamport-Stokes Oct 2 (Reuters) - World number one Jordan Spieth capped a sensational season on Friday when, as had been widely expected, he was voted the PGA Tour's Player of the Year after a 2014-15 campaign highlighted by two major victories among his five wins. Spieth landed the coveted honour after clinching the first two majors of the season -- the Masters and U.S. Open -- before finishing one shot out of a British Open playoff in July and being runner-up at the PGA Championship in August. The 22-year-old American ended his campaign in triumphant style with victory at the season-ending Tour Championship in Atlanta last week where he also clinched overall FedExCup playoff honours and the $10 million jackpot. More...