Replace lod with recursive_sequence_lengths in book examples

* Fix relu and log

* Update nn.py

Fix log and relu layer

* Fix mean iou op.

* Fix crop layer test.

* Fix unitest

* fix unitest.

* Fix average_accumulate_op for parallel executor.

* Fix model average on multi-GPUs.

Fix and enhance beam_search_op and beam_searc_decode_op

Fix dist train broadcasting bug

fix pserver sub-blocks

Fix async update failed

* 1. Remove PYTHON_FLAGS from paddle_build.sh in paddlepaddle/paddle:latest-dev

* 1. Add PYTHON_FLAGS back
2. Change SIGKILL to SIGINT and SIGTERM

* 1. Add setup.py.in back

* 1. add pip install open-cv in Dockerfile to avoid libusb_exit hanging up which is caused by the opencv-python package missing

* 1. Add the && \ to line above

* 1. Remove the notice comment

* "add some api reference"

* "fix based on preview"

* "fix evaluator"

* "remove template doc"

* "add doc for exec"

* "add more changes"

* "fix based on preview"

* "chagne code format"

* Make the CUDA kernel of concat correct and fix unit tests.