A Multinational, Multicenter, Randomized, Parallel-Group Study Performed in Subjects with Relapsing-Remitting Multiple Sclerosis (RRMS) to Assess the Efficacy, Safety and Tolerability of Laquinimod Over Placebo in a Double-blind Design and of a Reference Arm of Interferon B-1a (Avonex), in a Rater-Blinded Design, Teva Neuroscience.