Fix a wrong link in build doc

 fix documentation

refine compile_options.rst

Fix the config_parse.py if user does not set padding for Pool in the old config.

clang format .cc .h .cpp .c and .hpp file

Feature/add clang format plugin

Fix badge's wrong link in Readme

* Merge conflict using theirs

* Because it is a cuda source file, and we need to support c++ 03 in
  cuda.

* Different Type compare.
* ostream << should pass a const object.
* remove always true checks.

*  because baidu/paddle transfered to paddlepaddle/paddle

Fix a pointer comparison bug in hl_dso_loader.cc

Fix several cpp issues

* Because it is a cuda source file, and we need to support c++ 03 in
  cuda.

Add new badges for docs and stats