finding ALJ's hypothetical question to VE was proper as the limitation therein to "simple repetitive tasks" accounted for plaintiff's "moderate difficulties" in "concentration, persistence, and pace."

rejecting claimant's argument that the ALJ's hypothetical was incomplete because the limitation therein to "simple, repetitive tasks" did not account for plaintiff's moderate difficulties in concentration, persistence, and pace

applying Stubbs-Danielson instead of Brink noting that it did not find persuasive the Brink court's determination that the medical evidence did not establish any limitations in concentration, persistence or pace