Fix caching issues: plotly_util.js not being in a cache.
Fix caching issues: plotly_util.js not being in a cache.

TODO: all those dangling files should at least be concatenated,
but not minified

plotly/plotly.js,asolagmbh/plotly.js,etpinard/plotly.js,aburato/plotly.js,plotly/plotly.js,iongroup/plotly.js,iongroup/plotly.js,iongroup/plotly.js,asolagmbh/plotly.js,asolagmbh/plotly.js,aburato/plotly.js,etpinard/plotly.js,plotly/plotly.js,etpinard/plotly.js,plotly/plotly.js