upgrade webpack and webpack-dev-server

package.json

@@ -86,7 +86,7 @@
     "vue-router": "^3.0.1",
     "vue-template-compiler": "^2.5.13",
     "vuex": "^3.0.1",
-    "webpack": "^3.5.5",
+    "webpack": "^3.11.0",
     "webpack-bundle-analyzer": "^2.8.2",
     "webpack-stats-plugin": "^0.1.5",
     "worker-loader": "^1.1.0"
@@ -116,6 +116,6 @@
     "karma-webpack": "2.0.7",
     "nodemon": "^1.11.0",
     "prettier": "1.9.2",
-    "webpack-dev-server": "^2.6.1"
+    "webpack-dev-server": "^2.11.1"
   }
 }