Fix CP Toolbar permissions

#5802

A simpler solution - Instead of creating a compicated logic for CP access, let's make sure that all the hook_menu() functions define the proper access callback & arguments.

*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
Screenshots
*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*

Content Editors in VSite "john" have the permission "administer taxonomy":
![perm1](https://cloud.githubusercontent.com/assets/3273122/2641846/a3e36f24-beff-11e3-8d0c-d122a8c9e2bc.png)

*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*

Michelle is a Content Editor in VSite john, so she has the "administer taxonomy" permission:
![perm2](https://cloud.githubusercontent.com/assets/3273122/2641842/8f5629f2-beff-11e3-9f32-cee122275d42.png)

*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*

Before this PR, michelle cannot access Taxonomy pages:
![perm3](https://cloud.githubusercontent.com/assets/3273122/2641859/cd2f9c18-beff-11e3-9388-f67b9cf30cb9.png)

*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*

With this PR, michelle is able to access Taxonomy pages:
![perm4](https://cloud.githubusercontent.com/assets/3273122/2641862/de354058-beff-11e3-8669-95bb7aec824e.png)