Making old chart magic forward compatible with google.datalab (#250)
Making old chart magic forward compatible with google.datalab (#250)

* Fixing old call to Datasets that wasn't using context.

* Making old chart magic forward compatible with google.datalab.

yebrahim/pydatalab,googledatalab/pydatalab,supriyagarg/pydatalab,yebrahim/pydatalab,supriyagarg/pydatalab,craigcitro/pydatalab,craigcitro/pydatalab,jdanbrown/pydatalab,googledatalab/pydatalab,supriyagarg/pydatalab,parthea/pydatalab,yebrahim/pydatalab,jdanbrown/pydatalab,craigcitro/pydatalab,parthea/pydatalab,parthea/pydatalab,jdanbrown/pydatalab,googledatalab/pydatalab