CANADA STOCKS-China concerns, commodity prices drag TSX lower

* TSX down 53.68 points, or 0.35 percent, at 15,477.90 * All 10 main index sectors decline * First Quantum, Teck dragged down by copper price By John Tilak TORONTO, Sept 15 (Reuters) - Canada's main stock index dropped on Monday as worries about the pace of economic growth in China and weakness in commodity prices weighed on sentiment, pulling down shares in every major sector. Some economists cut their 2014 growth projections for China after figures released over the weeken