feat(auth): implement user authentication system

backend/node_modules/async/constant.js

@@ -0,0 +1,14 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+    value: true
+});
+
+exports.default = function (...args) {
+    return function (...ignoredArgs /*, callback*/) {
+        var callback = ignoredArgs.pop();
+        return callback(null, ...args);
+    };
+};
+
+module.exports = exports.default;