* cat exeception in request download; test=develop

* add re-try in download; test=develop

* Remove dependency on nltk for paddle __init__.
test=develop

* Remove nltk.movie_reivew sentiment dataset to remove dependency on nltk.
test=develop

* remove paddle.readers API. test=develop

remove the dependence of matplotlib  in dataset of uci_housing

* 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

* refine manual seed

* fix ci problem

* fix unittests

* fix unittest

* set is_init_py=false in manual_seed

* fix unittest

* fix bernoulli_op

* fix(unittest): change random_seed to manual_seed

* 🐞fix(unittest): fix manual_seed

* trigger ci

* fix test_sentiment

* fix test_imperative_save_load

* fix test_uniform_random_op

* fix test_uniform_random_op

* fix test_jit_save_load

* merge develop

* fix manual_seed

* fix manual_seed

* use global engine

* use shared_ptr

* fix double free

* fix bug

* fix bug

* fix bug

* fix test bug

* fix test bug

* fix test bug

* fix ci

* Make optimizer consistent in dygraph and static-graph and remove some LOG-INFO

* fix the compatiable problem between PY2 and PY3.

* add ut, test=develop

* add proxy, test=develop

* download dataset before test, test=develop

* change download log formate; test=develop

* add unittest for data download; test=develop

* remove cache before download; test=develop

replace mnist dataset url

* update CPU_NUM config
test=develop

fix flower-dataset unclose error

test=develop

test=develop

dataset_generator.py is a framework for generating data with python
the generated data with a fixed format will be feeded into c++ reader
test=develop

* add layer norm to Layers, add transformer prepare encoding

* little change

* finish encoder part

* add decoder part

* finish model part

* add test case and part of data feed

* add transformer test

* add to_parameter, add remove in set_attr

* test=develop, fix pos encoding bug, create_parameter with stantard name

* test=develop, rm dropout test in imperative

* test=develop, fix cpu error

* test=develop, fix minize bug

* test=develop, fix one hot not stop gradient

* test=develop, fix one hot not stop gradient

* test=develop, refine parameter name

* test=develop, fix transformer test in imperative mode

* test=develop, fix transformer test in imperative mode

* test=develop, fix boost and mkl download error

* test=develop, fix boost and mkl download error

* test=develop, fix ci and refine code

* test=develop, fix ci and refine code

* fix cdn issue, test=develop

* fix cdn issue, test=develop

test=develop

test=develop

test=develop

test=develop

test=develop