feat(auth): implement user authentication system

backend/node_modules/async/queue.js

@@ -0,0 +1,24 @@
+'use strict';
+
+Object.defineProperty(exports, "__esModule", {
+    value: true
+});
+
+exports.default = function (worker, concurrency) {
+    var _worker = (0, _wrapAsync2.default)(worker);
+    return (0, _queue2.default)((items, cb) => {
+        _worker(items[0], cb);
+    }, concurrency, 1);
+};
+
+var _queue = require('./internal/queue.js');
+
+var _queue2 = _interopRequireDefault(_queue);
+
+var _wrapAsync = require('./internal/wrapAsync.js');
+
+var _wrapAsync2 = _interopRequireDefault(_wrapAsync);
+
+function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
+
+module.exports = exports.default;