Fix for slightly different formatting between gallery and forum subcategories.

[drhamad]

The way forum & gallery sub-categories are displayed are slightly different.

Gallery:


Forum:


I think it'd be good to have gallery subcategories look just like forum subcategories.  The major differences that I notice right off are:
1) Comma's between each subcategory.
2) The table structure (forum subcategories are still to the right of the parent categories icon)