Home page featured scenes are not sorted by presence

[yakyouk]

The home page displays rooms sorted by presence count.
If there are more than 24 featured rooms and there are users in rooms not in the first 24 rooms returned by the paginated API, these rooms should still show up at the top of the list.

Sorting by presence count is done on client so rooms not in the first 24 rooms returned by the paginated API never appear on the list.
The paginated API should allow sorting directly by presence count server-side.

Understandably it may be complex since presence count is not an actual DB field.