Add prefetch interface on server side

* translate api standard

* Update api_doc_std_en.md

* fix typo

Make paddle.fluid no longer depends on paddle.v2

In this way we can build and test using WITH_FLUID_ONLY flag being set
to ON.

- move paddle.v2.dataset,reader to paddle.dataset,reader
- remove unused code (which depends on v2) in paddle.dataset,reader

* Add cpplint_pre_commit.hook

* Update hook

* Disable dropout_op_test.cc

* Remove cpplint.py but requires users to install their version

* fix cpplint error

* update v2/howto/cmd_parameter/index_en.rst

fix https://github.com/PaddlePaddle/Paddle/issues/8909/index_en.rst

* Update index_en.rst

update

* Update index_en.rst

fix punctuation & en.cmd

Fluid api

fix send_recv_op_test

Merge branch develop

Fix for failure in LRN op when MKLDNN is not used

fix compiler error of profiler_test in ONLY_CPU mode

Merge branch develop

kernels of IncrementOp

Fix server shutdown

* Translation for doc Model Configuration

* Adjust

Refine parallel

* fix data transform when op have inplace in/out

* add log

* should not delete scope because Compute maybe async

* optimize code

* add faq

* fix typo

Fix dist error with lr decay layer

* add prefetch_op

* fix ci

* optimize code

* optimize code

* fix include