A Randomized, Double-Blind, Placebo and Active-Controlled, 4-Arm, Parallel- Group, Multicenter Study Evaluate the Efficacy, Safety, and Tolerability of JNJ- 28431754 (Canagliflozin) Compared with Sitagliptin and Placebo in the Treatment of Subjects With Type 2 Diabetes Mellitus With Inadequate Glycemic Control on Metformin Monotherapy