adb command. return the subprocess.Popen object.

def raw_cmd(self, *args):
        '''adb command. return the subprocess.Popen object.'''
        cmd_line = [self.adb()] + self.adb_host_port_options + list(args)
        if os.name != "nt":
            cmd_line = [" ".join(cmd_line)]
        return subprocess.Popen(cmd_line, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)