ATHENS (Reuters) - Greece's Evangelos Venizelos quit as finance minister on Monday to lead the Socialists into a general election, a day after taking over the helm of the party, which is trailing far behind its rival conservatives in opinion polls. The socialist PASOK party, which came to power in October 2009 on a platform to tax the rich and help the poor but had to change course when the debt crisis exploded weeks later, has been weakened by over two years of unpopular austerity. ...