Test Plots on Travis: GKS can't open display

Awesome, thank you! Testing this now.
I’m not sure if you meant anything other than adding these two lines to the runtests.jl file:

ENV["PLOTS_TEST"] = "true"
ENV["GKSwstype"] = "100"

Or if there is anything else peculiar I need to add to the .travis.yml file.

(I also specify default(show=false) because none of my plots are actually displayed, they are all being saved to file)