Besides removing unnecessary imports, this also fixes the missing logger module in test_architectures.py within the static directory.

* add static notice

* add VisualDL and save best_model

* add VisualDLWriter callback

* update solov2 some detail

* fix check paddle version

* add enable_static()

* follow comments

* remove blank line

* Update docs
* Update README.md

* update check config

* fix slim/xx

* load inference

* add doc

* add config file for tensorrt_infer

* add padding for rcnn preprocess

* refine code & doc

* 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 export_model doc