Preserve colors for child processes

`stdio` was only used for win32. However the original NodeJS docs allow to use it everywhere http://nodejs.org/api/child_process.html#child_process_child_process_spawn_command_args_options
Checked: it perfectly works on Mac.
http://stackoverflow.com/questions/15339379/node-js-spawning-a-child-process-interactively-with-separate-stdout-and-stderr-s#comment24510829_16280786