Hotfix: 知乎用户动态 (#1080)

类型为 `question` 的动态，之前 `title` 与 `description` 取的字段是 `detail` 和 `excerpt`，导致标题出现 HTML 标签，类似乱码的效果，`description` 则内容不完整：
<img width="708" alt="wx20181106-142212 2x" src="https://user-images.githubusercontent.com/5186792/48046748-7fe59680-e1d0-11e8-8e44-d53b8f56f26d.png">

修改后的：
<img width="1387" alt="wx20181106-142307 2x" src="https://user-images.githubusercontent.com/5186792/48046762-925fd000-e1d0-11e8-9a12-86e1f4e71c24.png">

routes/zhihu/activities.js

@@ -57,8 +57,8 @@ module.exports = async (ctx) => {
                         url = `https://www.zhihu.com/pin/${detail.id}`;
                         break;
                     case 'question':
-                        title = utils.ProcessImage(detail.detail);
-                        description = detail.excerpt;
+                        title = detail.title;
+                        description = utils.ProcessImage(detail.detail);
                         url = `https://www.zhihu.com/question/${detail.id}`;
                         break;
                     case 'column':