* fix export_model doc link error

* sort out release/0.3 docs

* add new CHANGELOG

* add yolov4 in changelog

* add detailed doc
* add zh_CN doc of pssdet
* fix link

* Update docs
* Update README.md

* fix with_background in export model

* fix coco_eval background

* filter illegal data

* update warning message

update optimizer doc

* add map_fps fig

* test=master add some other lr scheduler

* test=master fix something and validate them

* add runtime log& script support set run_mode
* update code

* optimize python path

* add yolov4

* Organize and document mobile models

* Clean up trailing whitespaces

* Change bullet type

* Minor wording fixes

* Fix yolo naming

* Add link in repo README.md

* add serving export model
* add paddle serving client in requirement.txt
* remove redundant code with codestyle check
* fix export model doc
* fix according to professional reviews
* move paddle serving model export tutorial to the last of doc

* Make logger less noisy

* Fix indent