Co-authored-by: Ntangwei12 <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>

fix dnn dense var

fix bugs in dataset and metrics

add fgcnn and bug fix

update fasttest in readme

fix validation.py

add deep_crossing

update rank readme

add FNN and support load specific vars

Update rec_background.md

fix link of rec doc

update models of rank in front page readme