FEATURE #1358: add interface Authenticable to User model.

It seems that Laravel needs User models (users which are about to authenticate) to implement Authenticable interface.

app/Http/routes.php

@@ -28,7 +28,7 @@ Route::group(['middleware' => ['web']], function () {
     });
 
     // POST methods
-    Route::post('admin/login', 'Admin\Login@postLogin')
+    Route::post('login', 'Admin\Login@postLogin')
          ->name('login');
 });