Improving caching of static assets (#3591)

webapp/package.json

@@ -50,6 +50,7 @@
     "extract-text-webpack-plugin": "1.0.1",
     "file-loader": "0.8.5",
     "html-loader": "0.4.3",
+    "html-webpack-plugin": "2.22.0",
     "imports-loader": "0.6.5",
     "image-webpack-loader": "1.8.0",
     "jquery-deferred": "0.3.0",