Styles not applied when creating subplots

[sglyon]

cc @cc7768

Example:

using PlotlyJS
ms = Style(PlotlyJS.ggplot_style(),
                  layout=Layout(paper_bgcolor="#000000",       # "#EDEDED",
                                legend_x=-1.27, legend_font_size=10,
                                legend_orientation="h"))

p1 = plot(rand(10, 2), style=ms)
p2 = plot(rand(10, 2), style=ms)
p = [p1, p2]
display(p)  # not styled