update ale_data_set tests to be compatible with the new DataSet class (removing the batch_iterator test)
update ale_data_set tests to be compatible with the new DataSet class (removing the batch_iterator test)

davidsj/deep_q_rl,jcatw/deep_q_rl,spragunr/deep_q_rl,sygi/deep_q_rl,alito/deep_q_rl,alito/deep_q_rl,spragunr/deep_q_rl,davidsj/deep_q_rl,sygi/deep_q_rl,jcatw/deep_q_rl