Give devs more options for dynamically setting publicPath

assets/build/public-path.js

@@ -1,8 +1,7 @@
 /* eslint-env browser */
-/* globals WEBPACK_PUBLIC_PATH */
+/* globals SAGE_DIST_PATH */
 
-// Dynamically set absolute public path from current protocol and host
-if (WEBPACK_PUBLIC_PATH) {
-  // eslint-disable-next-line no-undef, camelcase
-  __webpack_public_path__ = `${location.protocol}//${location.host}${WEBPACK_PUBLIC_PATH}`;
+/** Dynamically set absolute public path from current protocol and host */
+if (SAGE_DIST_PATH) {
+  __webpack_public_path__ = SAGE_DIST_PATH; // eslint-disable-line no-undef, camelcase
 }