* add save model for step

* add PS/Collective support , add definition in yaml.md

* add check for QueueDataset while saving by step, modify dnn config yaml as an example

* add logging about model save operation

* fix bug for adding check for QueueDataset, modify dnn config yaml

* fix bug for dnn model config yaml

* fix bug for checking QueueDataset

* fix UT fail

* fix UT fail
Co-authored-by: Ntangwei12 <tangwei12@baidu.com>

* fix split files at PY3

* fix linux at PY3

* fix desc error

* fix collective cards and worknum
Co-authored-by: Ntangwei <tangwei12@baidu.com>

* add cluster running

* add k8s/paddle cloud

* fix local cluster without gpu

* define engine to train/infer/local_cluster_train/cluster_train

* fix gpu cluster wait

* fix bug for 2ps 2tr
Co-authored-by: Ntangwei <tangwei12@baidu.com>

* fix yaml import

* add value checker

* add development.md & update yaml.md

* fix tdm

* update general trainer

* update design

* rename model & reader

* update startup

* add gpu support

* after self-test

* code clean

* fix

* change dnn yaml

* add mpi support

* fix pslib

* fix pslib

* fix pslib network

* fix pslib program

* fix pslib runner

* fix fleet mode

* fix is_distribute

* fix deepfm

* change pslib code

* fix din

* update & fix

* fix reader base

* add ci & fix

* fix fnn

* fix ci sudo
Co-authored-by: Ntangwei <tangwei12@baidu.com>