A Non-randomized, Phase II Study of Eltrombopag in Combination With Rabbit Anti-thymocyte Globulin/Cyclosporine A (ATG/CsA) in Subjects With Moderate or More Severe Aplastic Anemia Who Have Not Received Prior ATG/Anti-lymphocyte Globulin (ALG)-Based Immunosuppressive Therapy - ICH GCP - Clinical Trials Registry