feat: Substitute the Backend URL dynamically

frontend/src/pages/register.tsx

@@ -10,7 +10,7 @@ import Snackbar from "@material-ui/core/Snackbar";
 
 import { withRouter } from "react-router-dom";
 
-import { BACKEND_URL } from "../config";
+import { BACKEND_URL } from "../config.in";
 
 interface IProps {
     history: any;

frontend/src/pages/review.tsx

@@ -31,10 +31,8 @@ import { ReviewType, IReviewMetadata } from "../models/review";
 import lev from "js-levenshtein";
 import {
     LEVENSHTEIN_MAX_DISTANCE, MAX_ERROR_THRESHOLD,
-    REVIEW_HELP_MOD
-} from "../config";
-
-import { BACKEND_URL } from "../config";
+    REVIEW_HELP_MOD, BACKEND_URL
+} from "../config.in";
 
 import { Queue } from "../utils/queue";