Admincenter Addon Navigation

Admincenter Addon Navigation
- Super Admin can create new Addon Categories with Name & Addon Links with Name, Url, Accesslevel, Sort Order
- Super Admin can sort Addon Categories & Addon Links except default Categories
- Default Categories are not editable/deleteable

![addon_edit_cat](https://f.cloud.github.com/assets/4713304/1813479/cc43d3c2-6ebf-11e3-950e-2e67cc8ea003.png)
![addon_edit_link](https://f.cloud.github.com/assets/4713304/1813480/cc44b5d0-6ebf-11e3-963c-b86e8c29c963.png)
![addon_new_cat](https://f.cloud.github.com/assets/4713304/1813481/cc44dbe6-6ebf-11e3-83d2-f25369d453ba.png)
![addon_new_link](https://f.cloud.github.com/assets/4713304/1813482/cc454694-6ebf-11e3-9976-69ce7b84e25b.png)
![addon_overview](https://f.cloud.github.com/assets/4713304/1813483/cc459fe0-6ebf-11e3-8afb-e26f2867dbe7.png)