xvfb-maybe

This package runs an arbitrary executable / args under xvfb-run if the
platform is Linux and DISPLAY isn't set. This is super useful for making
Electron unit tests run correctly in CI environments while still working
locally

Usage:

``sh


On Windows or OS X, this just invokes electron-mocha

On Linux, if we are in a headless environment, this will be equivalent

to xvfb-run electron-mocha ./test/*.js

xvfb-maybe electron-mocha ./test/*.js
``