Use Node.js 7 native async/await instead of babel

app.js

@@ -109,13 +109,11 @@ global.syzoj = {
         }).catch((err) => {
           this.log(err);
           res.locals.user = req.session.user_id = null;
-        }).finally(() => {
-          next();
         })
       } else {
         res.locals.user = req.session.user_id = null;
-        next();
       }
+      next();
     });
 
     // Active item on navigator bar

package.json

@@ -4,7 +4,7 @@
   "description": "An OnlineJudge System for OI",
   "main": "app.js",
   "scripts": {
-    "start": "babel-node app.js",
+    "start": "node --harmony-async-await app.js",
     "test": "echo \"Error: no test specified\" && exit 1"
   },
   "repository": {
@@ -25,8 +25,6 @@
   "dependencies": {
     "adm-zip": "^0.4.7",
     "ansi-to-html": "^0.4.2",
-    "babel-cli": "^6.18.0",
-    "babel-preset-es2017": "^6.16.0",
     "body-parser": "^1.15.2",
     "cookie-parser": "^1.4.3",
     "ejs": "^2.5.2",