cache headers

package.json

@@ -5,7 +5,6 @@
   "main": "dist/index.html",
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1",
-    "heroku-prebuild": "npm install pm2 -g",
     "heroku-postbuild": "gulp build"
   },
   "author": "Vojtech Sedlak",

server.js

@@ -45,7 +45,11 @@ app.use(helmet({
   }
 }));
 
-app.use(express.static(__dirname + '/dist'));
+app.use(express.static(__dirname + '/dist', {
+  etag: true,
+  lastModified: true,
+  maxAge: '1d'
+}));
 
 app.get('/', (req, res) => {
    res.sendfile(__dirname + '/public/index.html');