A Phase 1, Open-Label, Multicenter, Safety Study of Nivolumab (BMS-936558) in Combination with nab-Paclitaxel Plus or Minus Gemcitabine in Pancreatic Cancer, nab-Paclitaxel / Carboplatin in Stage IIIB/IV Non-Small Cell Lung Cancer or nab-Paclitaxel in Recurrent Metastatic Breast Cancer