Added a hook for visualization plugin to provide their demo datasets
Added a hook for visualization plugin to provide their demo datasets

motherjones/datawrapper,datafunk/datawrapper,rubensfernando/datawrapper,washingtonpost/datawrapper,devinit/datawrapper,rubensfernando/datawrapper,motherjones/datawrapper,shelsonjava/datawrapper,motherjones/datawrapper,elaOnMars/datawrapper,plusgut/datawrapper,shelsonjava/datawrapper,grepman/datawrapper,washingtonpost/datawrapper,datafunk/datawrapper,rubensfernando/datawrapper,devinit/datawrapper,devinit/datawrapper,ThuyNTran/datawrapper,motherjones/datawrapper,qqming113/datawrapper,washingtonpost/datawrapper,elaOnMars/datawrapper,devinit/datawrapper,datafunk/datawrapper,motherjones/datawrapper,elaOnMars/datawrapper,kendrick-k/datawrapper,robmcloughlin/Insights,kendrick-k/datawrapper,washingtonpost/datawrapper,rubensfernando/datawrapper,shelsonjava/datawrapper,plusgut/datawrapper,grepman/datawrapper,qqming113/datawrapper,grepman/datawrapper,devinit/datawrapper,elaOnMars/datawrapper,elaOnMars/datawrapper,ThuyNTran/datawrapper,motherjones/datawrapper,qqming113/datawrapper,qqming113/datawrapper,washingtonpost/datawrapper,rubensfernando/datawrapper,grepman/datawrapper,ThuyNTran/datawrapper,shelsonjava/datawrapper,datafunk/datawrapper,ThuyNTran/datawrapper,shelsonjava/datawrapper,robmcloughlin/Insights,robmcloughlin/Insights,qqming113/datawrapper,datafunk/datawrapper,kendrick-k/datawrapper,kendrick-k/datawrapper,datafunk/datawrapper,plusgut/datawrapper,elaOnMars/datawrapper,grepman/datawrapper,robmcloughlin/Insights,washingtonpost/datawrapper,robmcloughlin/Insights,ThuyNTran/datawrapper,kendrick-k/datawrapper,ThuyNTran/datawrapper,grepman/datawrapper,plusgut/datawrapper,shelsonjava/datawrapper,kendrick-k/datawrapper,qqming113/datawrapper,devinit/datawrapper