Keras Objectives and 0-based label (#458)
Keras Objectives and 0-based label (#458)

* keras objectives

* style

* alias

* accuracy

* meet review

* doc

* more doc

* python

* fix

* style

* fix scala ut

* fix python

* fix

* customloss

* predict classes

* python predict classes

* update

* update doc

* fix

* update

* update mapping

* meet review; add accuracy ut

* fix ut

* update doc

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