Lack of interest Smilies categories - update the "smilies" data registry to include them

[cclaerhout]

Currently it seems to have access to the smilies categories, we have to use the smilies model which would call a database request. It would be a good thing to have a direct access to them from the data registry:

XenForo_Model::create('XenForo_Model_DataRegistry')->get('smilies');