1. 增加微信退款接口 2. 增加取得卡券详情接口 3. 修改取卡券签名接口的说明 4. 将卡券核销接口的返回值由Void改为String Change-Id: I2bac2d090871a4988f7279a9794eca5722451cdd Signed-off-by: Liu Kai <liukai@tinkers.com.cn>