Efficacy and Safety of New Oral Budesonide-MMXÔ (CB-01-02) 6mg and 9mg Extended Release Tablet Formulations in Patients with Mild or Moderate, Active Ulcerative Colitis. A Multicenter, Randomized, Double-blind, Double Dummy Comparative Study Versus Placebo, With an Additional Reference Arm Evaluating Asacol^® 2400mg.