deps: add 'dev' script

package.json

@@ -4,6 +4,7 @@
   "description": "Vlad Faust's personal page",
   "private": true,
   "scripts": {
+    "dev": "webpack-dev-server",
     "build": "webpack"
   },
   "repository": {
@@ -26,6 +27,7 @@
     "sass-loader": "^7.0.1",
     "style-loader": "^0.21.0",
     "webpack": "^4.8.3",
-    "webpack-cli": "^2.1.3"
+    "webpack-cli": "^3.1.0",
+    "webpack-dev-server": "^3.1.8"
   }
 }