Modularize node, add step training

eval/epoch_configs/config_celeba.ini

eval/epoch_configs/config_celeba_100.ini

eval/epoch_configs/config_celeba_grow.ini

eval/epoch_configs/config_femnist.ini

eval/epoch_configs/config_femnist_100.ini

eval/epoch_configs/config_femnist_grow.ini

eval/ip_addr_7Machines.json

eval/step_configs/config_celeba.ini

eval/step_configs/config_celeba_100.ini

eval/step_configs/config_celeba_grow.ini

eval/step_configs/config_femnist.ini

eval/step_configs/config_femnist_100.ini

eval/step_configs/config_femnist_grow.ini