GitLab

* add gridsearch example for python sklearn

* reset_learning_rate->reset_parameter

* make callbacks public

Provide a high level Dataset class for easy use.

* add feature importances in python; add pandas support

* solve best_iteration issue

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

support init_score for multiclass classification (#62)

Support multiclass classification (#53)

quick fix for reading error: the rank.test data indeed has label