Merge pull request #88 from yandex/fix_version_ipykernel

fix version of ipykernel==4.3.1

Merge pull request #59 from yandex/fix_docker_build2

Fix docker build2

update test xgb

update root & xgboost installation method

Merge remote-tracking branch 'origin/master'

path fix

update all notebooks with new open physics datasets dependencies: htt…

…ps:https://archive.ics.uci.edu/ml/datasets/MiniBooNE+particle+ identification and https://archive.ics.uci.edu/ml/machine-learning-databases/magic/

small docs fixes

COPY -> CURL

minor changes to docstrings