Mootools isn't used in the category blog layout

This is a follow up PR from #3586. During testing we found that Mootools is still loaded in the blog layout.

### Testing
1. In Joomla 3.3 create a menu item for the articles category view using the blog layout.
2. Notice that /media/system/mootools-core.js and core.js gets loaded.
3. Apply PR and check that both files aren't loaded anymore.
4. Check that everything still works.

### Notice
If MooTools and core.js is still loaded, you may have to disable other modules like the login one.