ATHENS (Reuters) - Former Greek Prime Minister Alexis Tsipras' Syriza party would get 25 percent of the vote in a Sept. 20 snap election, versus 22 percent for the conservative New Democracy party, a University of Macedonia opinion poll showed on Friday. Tsipras abruptly resigned last week, days after clinching an 86 billion-euro (63 billion pounds) bailout package from European and International Monetary Fund lenders, hoping to crush a rebellion by far-left lawmakers and tighten his grip on power. ...