Set dynamically aboslute public path on 'npm run watch'; fix http/htt… (#1696)

* Set dynamically aboslute public path on 'npm run watch'; fix http/https hardcoded in watch.js

* WEBPACK_PUBLIC_PATH fix

assets/config.json

@@ -1,6 +1,7 @@
 {
   "entry": {
     "main": [
+      "./scripts/util/public-path.js",
       "./scripts/main.js",
       "./styles/main.scss"
     ],

assets/scripts/util/public-path.js

@@ -0,0 +1,8 @@
+/* globals WEBPACK_PUBLIC_PATH */
+
+// Dynamically set absolute public path from current protocol and host
+if (WEBPACK_PUBLIC_PATH !== false) {
+  /* eslint-disable no-undef */
+  __webpack_public_path__ = location.protocol + '//' + location.host + WEBPACK_PUBLIC_PATH;
+  /*eslint-enable no-undef*/
+}