display store_code next to Taxonomy for better selecting

If many stores having same taxonomy we struggle with selecting the right one.
Display the store_code next to
![2](https://f.cloud.github.com/assets/596169/2389353/c05fc86e-a94c-11e3-8fdf-ef0881361d7a.png)
 the Taxonomy for a better selecting. 

Issue #85