The new Chobani yogurt plant in Twin Falls opened in grand fashion — with speeches from political dignitaries and appearances by Olympic athletes and a marching band.  The New York-based yogurt maker celebrated Monday the opening of its second manufacturing plant. The 950,000-square-foot, $450 million facility will produce 4.2 million cases of Greek-style yogurt weekly.  Company officials say they will employ about 300 workers when operating at full capacity but anticipate expanding the payroll in the future with the development of new products.  Chobani CEO Hamdi Ulukaya called it a historic day — while Gov.  "Butch" Otter welcomed the company and encouraged Idahoans to eat more yogurt.  Others on hand included Lauren Cheney, of the U.S. women's gold medal soccer team, and Steven Lopez, a gold medalist in taekwondo.