FEATURE: use module_settings field instaed of config().

This way should be more reliable, because config() is available only after publishing module, however I can't publish module when it does not have config (module.json). In this way I can select all modules from database and generate module.json for each of them.

app/Handlers/Contracts/AppHandler.php

@@ -87,4 +87,11 @@ interface AppHandler
      * @param User $user model of logged user
      */
     public static function registerAdminMenu(User $user);
+
+    /**
+     * Install module
+     *
+     * @return mixed
+     */
+    public static function install();
 }