use styles in a module

I'm imposing a style inside a module, but it doesn't take effect when I call `PyPlot.jl` functions from this module. see [here](https://github.com/SimonEnsemble/Controlz.jl/blob/master/src/Controlz.jl#L5-L9).

```julia
module Controlz

using PyPlot

# hipster plot theme
PyPlot.matplotlib.style.use(joinpath(
replace(pathof(Controlz), "src/Controlz.jl" => "src"), "hipster.mplstyle"))
# ...

function my_plot()
plot([1], [2])
end
```
then the style is not used in `my_plot()`. is there a way to enforce my `.mplstyle` file to be used in these plots? thanks.