Delete entire boards from DataBoards when cleaning it gives us a 404.

This would happen when a board gets deleted, like /s4s/ hopefully one day.

src/databoard.coffee

@@ -65,14 +65,18 @@ class DataBoard
     $.set @key, @data
   ajaxClean: (boardID) ->
     $.ajax "//api.4chan.org/#{boardID}/threads.json", onload: (e) =>
-      board   = @data.boards[boardID]
-      threads = {}
-      for page in JSON.parse e.target.response
-        for thread in page.threads
-          if thread.no of board
-            threads[thread.no] = board[thread.no]
-      @data.boards[boardID] = threads
-      @deleteIfEmpty {boardID}
+      if e.target.status is 404
+        # Deleted board.
+        @delete boardID
+      else if e.target.status is 200
+        board   = @data.boards[boardID]
+        threads = {}
+        for page in JSON.parse e.target.response
+          for thread in page.threads
+            if thread.no of board
+              threads[thread.no] = board[thread.no]
+        @data.boards[boardID] = threads
+        @deleteIfEmpty {boardID}
       $.set @key, @data
 
   onSync: (data) ->