increased pie label font size to 12px
increased pie label font size to 12px

SylvainCorlay/bqplot,dmadeka/bqplot,ChakriCherukuri/bqplot,SylvainCorlay/bqplot,ChakriCherukuri/bqplot,dmadeka/bqplot,bloomberg/bqplot,SylvainCorlay/bqplot,bloomberg/bqplot,bloomberg/bqplot,ChakriCherukuri/bqplot