cherry-pick add aistudio link in README #3568 (#3585)

* add_multiprocess_train_to_image_classification

test=develop

* update TensorRT 1.5.2 inference time

* add EfficientNet configuration in README

* add notes for the ported weight of EfficientNet

Add EfficientNet

* fix mobilenet bug

* fix inplce warning

refine image classification and add 19 pre-trained models.

* remove use_inplace=True and add save_step params

* remove useless params when using global pooling

fix lsr bug in image classification

* Refine Image classification

This reverts commit 5e41760f.

* fix SENet154_vd name

* add_license for PaddleCV

* update license date

* update GAN license date

* add densenet, squeezenet, darknet, resnext, resnext101_wsl pretrained models

* fix gpu detection issue on windows
1. use the fluid.core.get_cuda_device_count() to decide the GPU number
2. ignore the path missing issue

* add mobilenet_v2_x0_5, resnext50_32x4d, resnext50_64x4d, xception41 pretrained models
* Update README_cn.md

* Transfer resnext50 multi-process multi-gpu changes from benchmark to models
Signed-off-by: Nzhaoyuchen <zhaoyuchen01@baidu.com>

* refine code
Signed-off-by: Nzhaoyuchen <zhaoyuchen01@baidu.com>

* Reduce buf size in image_classification/reader
* Fix format

* refine readme and fix train bug

* Including Fluid and Fluid-TensorRT inference time.

* Add readme and disable memopt

memopt may affect GC result

test=develop
Signed-off-by: Nzhaoyuchen <zhaoyuchen01@baidu.com>

* Disable memopt as GC opend

test=develop
Signed-off-by: Nzhaoyuchen <zhaoyuchen01@baidu.com>

* set lr.persistable=True

* comment fuse flag

This changing can improve performance

test=develop

* fix padding bug and add resize_short_size args

* fix typo

* pass args:settings in eval and infer