add vg.json export/save option for vega-lite spec previews #56
Description
see this code bit from vega-unfurl repo for more info :)
https://github.com/RandomFractals/vega-unfurl/blob/master/app.js#L72
{{ message }}
see this code bit from vega-unfurl repo for more info :)
https://github.com/RandomFractals/vega-unfurl/blob/master/app.js#L72