* add warning log for DataLoader output format imcompatible upgrade. test=develop

* add unittest. test=develop

* fix ci converage. test=develop

* fix ci coverage. test=develop

* add random state generate in DataLoader worker. test=develop

* fix license and __all__. test=develop

* fix unittest. test=develop

* add dict/str/list supprot for DataLoader. test=develop

* fix dataloader collate return list mix tensor and numpy array. test=develop

As the title 

* fix failed tests in yingchun gived list

* add unittests into static_mode_white_list

* add enable static

* fix dist unittest

* skip test_sigmoid_focal_loss_op & add gym

* revert no need skip unittests

* remove gym

* add paddle.io.ComposeDataset & paddle.io.ChainDataset. test=develop

* add TensorDataset. test=develop