By Fedja Grulovic and Fatos Bytyci MITROVICA, Kosovo (Reuters) -Minority Serbs in the north of Kosovo said on Saturday they were quitting their posts in state institutions including the government, police and courts to protest Pristina’s order for them to start using Kosovo vehicle licence plates. The long-running licence plate row has stoked tensions between Serbia and its former province of Kosovo, which gained independence in 2008 and is home to a small ethnic Serb minority in the north that is backed by Belgrade. Following a meeting of Serb political representatives in the north of Kosovo,…