How to change the color of bars in boxplot Gadfly and add minor ticks in the vertical axis?

Hi, please how could I change the color of the bars of the boxplot below, from deepskyblue to RGB = [0,9, 0,4, 0.2]?

And how could I add a few minor ticks in the vertical axis, if possible pointing outside the the plot area?

using Gadfly, Rdatasets

iris = dataset("datasets", "iris")
p = plot(iris, x=:Species, y=:SepalWidth, Geom.boxplot);
draw(PDF("myoutput.pdf", 10cm, 8cm),p)

Thank you!