* check md5 before load weights.

* check md5 after weights download

* add roadsign_voc dataset and update FAQ

* Add roadsign_voc dataset, updatea FAQ.md, and add yolov3_voc and yolov3_coco config template files.

* remove configs/templates

* convert config template file to md file, update comment

* mv config annotation file to config_annotation.

* move to docs/advanced_tutorials/config_doc

* rename

* update style

* update 2019-->2020

* update yolov3_mobilenet_v1_roadsign.md

* addd preprocess as yolov3_reader

* remove yolov3_mobilenet_v1_roadsign.md and add yolov3_mobilenet_v1.md

* fix typo

* fix voc dataset and docs

* add custom datsset demo

* Make logger less noisy

* Fix indent

* add yolov3_mobilenet_v3

* Polish Reader to simplify preprocessing logic.
#  sample_transforms-> make batch -> batch_transforms in Reader.
* Clean some code
* Imporve yolov3_r50vd_dcn_obj365_pretrained_coco 41.4 to 41.8.
* Update all configs.

* add info for obj365 download

* update code & doc

* change voc_loader

* add face doc
* update face detection readme and add demo jpg

* refine download sh to py

* update QUICK_STARTED

* Initial support for distributed training

* Housekeep on rank 0 only

* Conform to models convention

* refine auto download logs

* add gn doc

* refine weight download

* fix comment

* fix easy problem

* fix infer doc and config default

* refine dataset exists

* fix None proc

* Rename object_detection to PaddleDetection
* Small fix for doc