Fix PKU EECS Notification Link return 404 (#623)

1. fix item link 404 error 
2. add default title

routes/universities/pku/eecs.js

@@ -21,7 +21,7 @@ module.exports = async (ctx) => {
     const text = $('.hvr-shutter-out-vertical');
 
     ctx.state.data = {
-        title: '',
+        title: '北大信科通知',
         link: host + 'Survey/Notice/?Mtitle=' + type,
         description: '北大信科 公告通知',
         item:
@@ -31,7 +31,7 @@ module.exports = async (ctx) => {
                     item = $(item);
                     return {
                         title: item.find('p').text(),
-                        link: host + item.attr('href'),
+                        link: host + 'Survey/Notice/' + item.attr('href'),
                         description: item.find('p').text(),
                         pubDate: item.find('em').text(),
                     };