Download data button at Table of aggregates visualization

[trickvi]

Moved from openspending/openspending#641

Hello there. I don't know if this is a known issue but there's a bug when trying to download data generated by a "Table of aggregates" visualization, the "Data" button [last one in the bottom right of the table] isn't working.

By looking at the console I have an error at the getDownloadURL function [line 53 of main.js] where the var data is undefined.