GitLab

* Read and write datsets from hdfs.
* Only enabled when cmake is run with -DUSE_HDFS:BOOL=TRUE
* Introduces VirtualFile(Reader|Writer) to asbtract VFS differences

* add network apis.

* support parallel loading dataset in c api.

* fix bug

* fix bug

* finish the data loading part

* allow prediction.

* fix bug for decision type.

* finish split finding part

* fix bugs.

* bug fixed. add a test .

* fix pep8 .

* update documents.

* fix test bugs.

* fix a format

* fix import error in python test.

* disable missing handle in categorial features.

* fix a bug.

* add more tests.

* fix pep8

* fix bugs.

* remove the missing handle code for categorical feature.

* change whitespace to underline in feature names

* add test

* fix bug

* fix bug

* warning -> fatal

* refine prediction logic.

* fix test.

* fix out_len in training score of Dart.

* improve predict speed for high dimension data.

commit 70f88c54f6820d4c3824d97b34042c617fb21635
Author: Guolin Ke <i@yumumu.me>
Date:   Wed Feb 22 19:40:10 2017 +0800

    futher reduce guided

commit f54620b807c68f5ac6cef521d787ca2750efe464
Author: Guolin Ke <i@yumumu.me>
Date:   Wed Feb 22 19:32:36 2017 +0800

    avoid to use guided

* Added possibility to compile without openmp (useful for clang on Mac)

* Added CMake option to create dylib on MacOS

Categorical feature support (#108)

1. merge python-package
2. add dump model to json
3. fix bugs
4. clean code with pylint
5. update python examples