* support --eval for s2anet

* add spine dataset and config yml for s2anet

* add doc for s2anet

* update doc

* fix typo, test=document_fix

* add some comments, and update import

* add mot data

* fix operators, source

* fix data source transform

* fix parse_dataset register_op

* fix scale_factor, RandomAffine

* add assert for check

* fix ci

* Add BottomUp HigherHRNet for pose.
* reverse xtcocotools to pycocotools

* pose bottomup higherhrnet: data
* mv common function to ppdet modeling;
* fix code style

* refine trainer

* add blazeface & update rcnn modelzoo

* remove condition num_priors

* refactor rcnn, test=dygraph

* add mask_rcnn, test=dygraph

* add Faster RCNN & Faster FPN, test=dygraph

* update according to the review, test=dygraph

* ppdet installable

* exit1 in travis failed

* Add cascade_rcnn_cls_aware_r200_vd_fpn_dcnv2_nonlocal_softnms model on oidv5 and obj365.
* Add obj365 config annotation
* Update docs.