Release 0.7.1

Major Features And Improvements

• Python wrapper: added methods to download datasets titanic and amazon, to make it easier to try the library (catboost.datasets).
• Python wrapper: added method to write column desctiption file (catboost.utils.create_cd).
• Made improvements to visualization.
• Support non-numeric values in GroupId column.
• Tutorials section updated.

Bug Fixes and Other Changes

• Fixed problems with eval_metrics (issue #285)
• Other fixes