* set lr.persistable=True

* comment fuse flag

* move benchmark changing of cycle gan to models/develop, test=develop

* add flag exist check, test=develop

This changing can improve performance

test=develop

* add ce for dygraph mnist

* add ce for dygraph mnist

* del mnist_dygraph.py

* change mnist_dygraph to train

* fix print style

* add multi process reader

* use distributed_batch_reader

* update

* fix

* Enable the use of python multi-processes to read data.

* Add the setting of default value of some paddle flags, such as GC.

* update transformer

* Update the optimization of PaddingRNN model in benchmark repo.

* Move the configuration of rnn model to a serapate file.

* Fix the error of forgetting feeding learning_rate when use py_reader.

* Add a argument and some check.

* Fix the feeding problem and remove some build options.

* Add some comments and refine the format.

* Fix an error when define the inference program.

* Remove the setting of use_experimental_executor, and simplfy some codes.

* Refine the setting of device_count.

load_persistables function returns a tuple which include parameters and optimizer

* fix padding bug and add resize_short_size args

* fix typo

* pass args:settings in eval and infer

* Fix SSD file path.

* Move object_detection to ssd.

1.Modify the checkpoint save path
2. Modifiy the img save paht
3. Synchronous modification for Readme
4. update generated result img

* add landmark models

* modify single queue to a queue per process for data processing

* add transforms.py and rename torchvision_reader.py to reader.py

* add datasets.py

* remove pytorch apis

* fix some small bugs

* remove torch and torchvision from requirements.txt

* modify core.CUDAPlace to fluid.CUDAPlace

* bug fix: data_dir has no effect

* bug fix: data_dir has no effect

* bug fix: modify  in directory

* bug fix: fix a typo in README.md

* update image classification pretrained models

* update softmax

* Add mixup and distill and fix bugs

* recover test pyreader

* add error tip

* update README_CN

* fix distill bug

* add reader_cv2.py

* update run.sh

* fix docs

* fix typo

* polish train.py

* fix typo

* remove commented code

* fix typo

* fix_typo

* recover scale_loss

* fix typo

* fix bug

* fix test_program bug

* Update README.md

* add ACL2019-DuConv

* use py_reader and support multi-card training

* update README

fix load bug

* add yolov3 label_smooth faq

* refine en

* fix bug in cycle and pix

* add ce for models_ce

* add ce for sentiment_classification

* Add an option to control whether to load ERNIE using PaddleHub

* Update README

* add yolov3 save_inference_model example

* add save_inference_model in infer.py

* refine link

* refine yolov3 doc en.

* fix format in README.md

* refine FAQ

* refine en doc

* add zh doc

* refine zh doc

* use zh as default

* add infer config

* add data descp