Applying a custom taxonomy weight.

Relate to issue #2500 
The problem of the in consistent ordering of the terms come the fact that the hierarchical taxonomy order the terms by their depth and didn't take care of the term's weight. I added a custom order function.

Screen shot attached.
![Selection_082](https://f.cloud.github.com/assets/1222368/419114/6dd0b9dc-acc2-11e2-8a4f-deb59ab4479d.png)