Lapatinib Active Not Recruiting Phase 2 Trials for HER2/Neu Positive / Stage IV Breast Cancer / Stage IIIB Breast Cancer / Stage IIIC Breast Cancer AJCC v7 / Stage IV Breast Cancer AJCC v6 and v7 / Recurrent Breast Carcinoma / Stage IIIB Breast Cancer AJCC v7 / Stage IIIC Breast Cancer Treatment