Nyaggle

- replace `experiment_gbdt` with `run_experiment` 27
- support xgboost 21
- add `cached_feature` decorator 28
- fix categorical feature handling 22

- Fix module `nyaggle.feature` module couldn't be found from pip package

- with_id option to support atmaCup3 format :)

- Fix pip package

- hotfix around binary-classification
- add example