GitLab

* fix creating valid_sets

* support both list and dict

* update Python-API.md

* remove other parameters in sklearn fit

* add dart parameters to sklearn init

* add troubleshooting

* use unittest

* update unittest version

* fix test_engine.py

* fix test_sklearn.py

* default eval_metric by subclass

* add test grid search

* remove verbose_eval

* add gridsearch example for python sklearn

* reset_learning_rate->reset_parameter

* make callbacks public

* clean python docs

* clean python docs

* add python doc

* add boosting_type to python sklearn

* fix error