BRUSSELS (Reuters) - A European Union summit ended abruptly on Friday after leaders failed to reach agreement on the bloc's long-term budget, following a two-day stand-off between poorer countries and "frugal" member states seeking to rein in spending.Summit chairman Charles Michel gathered the 27 national EU leaders at the end of the day to bridge divisions, but they broke up within minutes after rival camps rejected a compromise plan he had proposed."We have to acknowledge that the differences..