Add start and build script to demo (#12)

* Add a start script to demo

* Add build script to demo

Author: CodinCat

demo/package.json

@@ -4,12 +4,17 @@
   "description": "A demo application using react-perimeter",
   "main": "index.js",
   "license": "MIT",
+  "scripts": {
+    "start": "webpack-dev-server --progress",
+    "build": "webpack --progress"
+  },
   "devDependencies": {
     "babel-loader": "^6.4.1",
     "babel-preset-es2015": "^6.24.0",
     "babel-preset-react": "^6.23.0",
     "halogen": "^0.2.0",
-    "webpack": "^2.2.1"
+    "webpack": "^2.2.1",
+    "webpack-dev-server": "^2.4.2"
   },
   "dependencies": {
     "babel-core": "^6.24.0",