* 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 moile-side rcnn server model

fix rcnn server side rcnn models' pretrain path

* add server side rcnn model, 62 fps with coco mAP 41.6% and 20fps with coco mAP 47.8%

* 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 softnms, nonlocal, resnet200_vd_backbone
* add CBNet
* update model zoo

* add multi-scale test

* add cascade gn

* add cascade mask gn config

* update configs

* fix infer doc and config default

* refine dataset exists

* fix None proc

* Clean up a bit

* Add `__shared__` annotation for shared variables between modules

* Dedup `num_classes` configurations

* Document `__shared__` usage

* Remove some unused variable

* Improve docstring and add comments for `__shared__`

* Rename object_detection to PaddleDetection
* Small fix for doc