接口：https://api.mch.weixin.qq.com/pay/facepay
传参： String a = "appid=" + PayUtils.APP_ID
                + "&body=test"//**
                + "&face_code=" + face_code//**
                + "&mch_id=" + PayUtils.MCH_ID
                + "&nonce_str=" + PayUtils.NONCE_STR//**
                + "&openid=" + openID//**
                + "&out_trade_no=" + outTradeNo//**
                + "&sub_mch_id=" + PayUtils.SUB_MCH_ID//**
                + "&total_fee=1";