chore(package): update html-webpack-plugin to version 4.0.1

Closes #58

Author: greenkeeper[bot]

package.json

@@ -57,7 +57,7 @@
     "eslint-loader": "^3.0.2",
     "eslint-plugin-import": "^2.17.2",
     "file-loader": "^5.0.1",
-    "html-webpack-plugin": "^3.2.0",
+    "html-webpack-plugin": "^4.0.1",
     "jest": "^23.6.0",
     "jsdoc": "^3.5.5",
     "jsdom": "^12.0.0",