Support shell out/err splitting and exit codes about goadb HOT 1 OPEN

func (c *Device) RunCommand(cmd string, args ...string) (string, error) {
    exArgs := append(args, ";", "echo", ":$?")
    outStr, err := c.commandOutput(cmd, exArgs...)
    if err != nil {
        return outStr, err
    }
    idx := strings.LastIndexByte(outStr, ':')
    if idx == -1 {
        return outStr, fmt.Errorf("adb shell error, parse exit code failed")
    }
    exitCode, _ := strconv.Atoi(strings.TrimSpace(outStr[idx+1:]))
    if exitCode != 0 {
        err = ShellExitError{strings.Join(args, " "), exitCode}
    }
    outStr = strings.Replace(outStr[0:idx], "\r\n", "\n", -1)
    return outStr, err
}