A Randomized, Double-Blind, Double-Dummy, Placebo Controlled, Parallel-Group, 12-Week Clinical Study to Assess the Efficacy and Safety of 320 or 640 mcg/Day of Beclomethasone Dipropionate Delivered Via Breath-Actuated Inhaler (BAI) or Metered-Dose Inhaler (MDI) in Adolescent and Adult Patients 12 Years of Age and Older With Persistent Asthma