(Reuters) – Prime Minister David Cameron is to chair a meeting of the government’s emergency response committee on Sunday to discuss an Islamic State (IS) video showing the beheading of British aid worker David Haines. IS militants fighting in Iraq and Syria released the video on Saturday. Reuters could not immediately verify the footage, but the images were consistent with those of the filmed executions of two American journalists, James Foley and Steven Sotloff, in the past month. Cameron, […]