Facebook CEO Mark Zuckerberg has warned of the possibility of civil unrest as the votes for US presidential elections are tallied and he said that the day would be a test for the social networking site. Zuckerberg said he is worried that with America so divided and election results potentially taking days or weeks to be finalised, there is a risk of civil unrest. <br /><br />#Facebook #MarkZuckerberg #CivilUnrest
