Added Distributed sampler option

Fix style

Merge pull request !3549 from anthonyaje/device_augment_mapop_refactor1

Merge pull request !3553 from tony_liu2/staging

Merge pull request !3739 from laiyongqiang/eliminate_memcpy_bug

Merge pull request !3119 from dengyutao/remove_blockreader

Merge pull request !3537 from riemann_penn/add_sparse_operator

Merge pull request !3727 from xiefangqi/fuzz_issue_pad_01

Merge pull request !3645 from chenzhongming/master

Merge pull request !3671 from ms_yan/vgg_optimize

add mindspore.hub and change model_zoo

Merge pull request !3657 from yangzhenzhang/add-stridedslice-op

Merge pull request !3405 from gziyan/fix_optimizer_parallel

fix line lengths

fix spacing

reverse a few changes

Merge pull request !3574 from hewei/rename_user_data_func

Merge pull request !3603 from jiangzhiwen/fix_column_names_exceeded

Merge pull request !3620 from 张学同/to_merge

Merge pull request !3612 from changzherui/mod_case

Refactored MapOp to in preparation to support device augment

Minor fix

Merge pull request !3394 from XunDeng/pp_poc_v3

Merge pull request !3551 from nhussain/fix_cpp_only_build

Merge pull request !3543 from lianliguang/unify-primitive

Merge pull request !3472 from Xiaoda/13-add-gpu-costmodel

Merge pull request !3528 from Simson/push-to-opensource

Merge pull request !3435 from yangzhenzhang/add-tile-op

added cdf, logcdf, survival, logsurvival, entropy, mode, cross_entropy wrapper

Merge pull request !3449 from MahdiRahmaniHanzaki/cifar100-c-api

merge the script

optimize the script

Merge pull request !3519 from anzhengqi/remove-log

Merge pull request !3500 from lirongzhen1/master