Categorical histogram

How can I set the order of the groups? Julia tends to reshuffle them randomly. And how can I add a second row with a bracket and its own name to show that G1 and G2 are part of a subgroup called Gprime?

ctg = repeat(["Category 1", "Category 2"], inner = 5)
nam = repeat("G" .* string.(1:5), outer = 2)

groupedbar(nam, rand(5, 2), group = ctg, xlabel = "Groups", ylabel = "Scores",
        title = "Scores by group and category", bar_width = 0.67,
        lw = 0, framestyle = :box)