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.
Setting this will cause e.g. `steroids make` to crash with error `[TypeError: Cannot call method 'on' of null]` (however, the child process is still spawned). This is caused by lines 63-65. If you comment them out, everything kinda seems to work, but I remember there being some other bug that caused us to remain with the non-`stdio: 'inherit'` version back in Fall 2013 when were last exploring this. Maybe explore further if you can find any bugs with `stdio: 'inherit'` enabled?