(Adds futures, company news items) Aug 14 (Reuters) - Britain's FTSE 100 index is seen opening up 17 points on Monday, according to financial bookmakers, with futures up 0.3 percent ahead of the cash market open. * DX GROUP/JOHN MENZIES: British mail delivery company DX Group said on Monday talks for a potential merger with John Menzies Plc's distribution unit had been terminated due to unsuitable terms. * TELIT: Telit Communications said CEO Oozi Cats resigned after an indepen