add back serve favicon

package.json

@@ -22,6 +22,7 @@
     "html-webpack-plugin": "^2.24.1",
     "lru-cache": "^4.0.1",
     "serialize-javascript": "^1.3.0",
+    "serve-favicon": "^2.3.0",
     "vue": "^2.0.0",
     "vue-router": "^2.0.0",
     "vue-server-renderer": "^2.0.0",