Heatmap color palette

[bpostlethwaite]

use the new https://github.com/plotly/react-colorscales under the hood. test

[bpostlethwaite]

(also should show automatically for any plot type needing a colormap... "should just work")

[VeraZab]

for reference: currently what we have in plotly/create is this one:

@aulneau what would you say of taking a shot at this widget?

[nicolaskruchten]

Is anything more needed for this issue or can we close it? I've got the new widget in place for the heatmap now and it works great