* add Tensor support for sub-functions of colorjitter
* add UT

* Update transforms.py

* Update transforms.py

* Update transforms.py

* Update functional.py

* update 2.0 public api in vision

* fix some flake8 errors

* add to_grayscale, normalize

* add rotate

* add vfip and hflip

* add crop center_crop


* add padding, support constant, reflect, replicate, circular same as paddle.pad

* add get-image-[n,c,w,h] axis utils

* fixed docs.

* Fixed docs. test=document_fix

code bak.

fixed docs. test=document_fix

* Revert to previous version of python/paddle/fluid/backward.py

* fixed bugs.

* test=document_fix. Fixed examples.

* Modified params of some APIs to support tuple and list.

* fixed bug.

* fix cv2 rotation

* update to_tensor en docs

* add pil backend

* rm dependence of cv2

* Move hapi form paddle/incubate to paddle

* Remove vision/datasets/utils.py and clean code

* Add sample code for conll05

* Print pull path when saving model

* Fix sample code after paramter_list of SGD is changed to parameters

* Fix bug in wmt16 datase

* fix bug

* add more vision transfrom apis

* add vision

* fix predict, test=develop

* add unittest for vision apis, test=develop

* fix typos

* add hapi models api, test=develop

* fix code format, test=develop

* fix typos, test=develop

* fix sample code import, test=develop

* fix sample codes, test=develop

* add decompress, test=develop

* rm darknet, test=develop

* rm debug code, test=develop