OKLAHOMA CITY, 2016-Feb-09 — /EPR Retail News/ — SONIC Drive-In (NASDAQ: SONC), the nation's largest chain of drive-in restaurants, is raising the bar for breakfast quality by announcing a partnership with Keurig Green Mountain, Inc. (NASDAQ: GMCR), a personal beverage system company, to offer hot, fresh Green Mountain Coffee®. The addition of Green Mountain Coffee®…