Add --verbose option to %bigquery sample
Add --verbose option to %bigquery sample

Issue #618

yebrahim/datalab,craigcitro/datalab,yebrahim/datalab,parthea/datalab,googledatalab/datalab,craigcitro/datalab,parthea/datalab,craigcitro/datalab,googledatalab/datalab,craigcitro/datalab,parthea/datalab,googledatalab/datalab,parthea/datalab,parthea/datalab,craigcitro/datalab,googledatalab/datalab,parthea/datalab,yebrahim/datalab,yebrahim/datalab,googledatalab/datalab,yebrahim/datalab,googledatalab/datalab