Erlotinib Completed Phase 1 Trials for Recurrent Osteosarcoma / Recurrent Childhood Ependymoma / Recurrent Childhood Cerebral Astrocytoma / Recurrent Childhood Rhabdomyosarcoma / Recurrent Childhood Cerebellar Astrocytoma / Recurrent Childhood Medulloblastoma / Recurrent Neuroblastoma / Previously Treated Childhood Rhabdomyosarcoma / Recurrent Childhood Malignant Germ Cell Tumor / Recurrent Childhood Soft Tissue Sarcoma / Recurrent Childhood Brain Tumor / Recurrent Childhood Supratentorial Primitive Neuroectodermal Tumor Treatment