Fix confusion matrix when datasource is BigQuery. (#463)
Fix confusion matrix when datasource is BigQuery. (#463)

* Fix confusion matrix when datasource is BigQuery.

* CR comments.

yebrahim/pydatalab,googledatalab/pydatalab,supriyagarg/pydatalab,craigcitro/pydatalab,yebrahim/pydatalab,googledatalab/pydatalab,googledatalab/pydatalab,supriyagarg/pydatalab,supriyagarg/pydatalab,craigcitro/pydatalab,craigcitro/pydatalab,yebrahim/pydatalab