Some improovements

Hi there!

Thank you very much for developing this awsome version of django admin. I have decided to start one business management project for one of my clients based on your framework. 
While I was working on it I last week I have found few things to improoved it a little. 

This pull request adds Lithuanian translations, support for custom Use Model in django 1.5, and menu items ordering based on a sequence they have been registered instead of alphabetic order.