Moved 'db_instance' from class ``Clerk`` to 'database' module.
Moved 'db_instance' from class ``Clerk`` to 'database' module.

daviddeng/azrael,olitheolix/azrael,olitheolix/azrael,olitheolix/azrael,daviddeng/azrael,daviddeng/azrael,daviddeng/azrael,daviddeng/azrael,olitheolix/azrael,olitheolix/azrael