afero.ReadDir sorts ReadDir entries. Nooooooo!

[LandonTClipp]

func ReadDir(fs Fs, dirname string) ([]os.FileInfo, error) {
	f, err := fs.Open(dirname)
	if err != nil {
		return nil, err
	}
	list, err := f.Readdir(-1)
	f.Close()
	if err != nil {
		return nil, err
	}
	sort.Sort(byName(list))
	return list, nil
}

This is super bad because it means we are wasting time sorting even if we don't want to. Very bad for large directories, and it means it is non-configurable. Will need to write our own ReadDir.