Downgrade the Sphinx to use 1.5.6

* Add Python 3 support

* Update protobuf to 3.5 and pybind to 2.2.2

* Update test scripts to use python -m

* Change zip/xrange/import usages

* Remove file generated by

* Graph viz set up (#282)

* Include the Graph requirement, GraphViz` in docs.

* Provide information to the ONNX format model export.

* Ask the user to download Graphviz via the website instead of brew.

* Make test and build scripts compatible with python 2 & 3

* A WITH_PYTHON3 option was added to cmake.

* setup.py will detect runing version python, and setup up WITH_PYTHON3 environemnt variable before calling build.sh

* build.sh and test.sh will handle WITH_PYTHON3

* Fix pybind warning

* Pass WITH_PYTHON3 correctly

* Fix coding style

* Add six for Python 2 and 3 Compatibility

* Fix coding style

* Binary Record Fixes

* Fixed issues with binary_record.h filename generator method.  std::hash is not consistent across OS.  It will generate different hash's when ran on different OS on the same string.  Change the filename generator to use a static counter.  It will be more ideal to use UUID generator available in boost 1.4.2, however, boost 1.4.2 has problems compiling on c++11 \n* Fix issue with pytorch demo where it logs to the absolute path /workspace

* Fix performance issue on server when server fails to load image file.  Currently server retries an API call 3 times before it fails, at which point it'll sleep the thread for 2 secs.  This becomes problematic when there are alot of SDK errors.  I'll create seperate issue to refine the retry logic to not be so expensive on the server.

* Add travis-ci job to deploy docs to visualdl.paddlepaddle.org.  Update readme's to correctly show all images.

* Add SSH known hosts

* Add in additional restrictions for documentation deploy:
* Only deploy on merge to 'develop' branch

Update the requirements.txt to include pre-commit