New folder structure, new artisan commands, namespaces and some improvements

- Now the default directory module is in the folder `app/`. 
- New folder structure 
- Using namespace 
- Improvement in console commands 
- Added new artisan commands
  ```
  php artisan module:provider

  php artisan module:migrate-rollback

  php artisan module:migrate-reset

  php artisan module:migrate-refresh
  ```