Moved filter of nodes of type blog to the node storage layer.

This is more efficient because the result set from the query will be smaller and it will be easier to implement the pagination

modules/node/persistence/cms_node_storage_null.e

@@ -41,12 +41,12 @@ feature -- Access: node
 			create {ARRAYED_LIST [CMS_NODE]} Result.make (0)
 		end
 
-	nodes_order_created_desc: LIST[CMS_NODE]
+	blogs: LIST[CMS_NODE]
 			-- List of nodes ordered descending by creation date
 		do
 			create {ARRAYED_LIST [CMS_NODE]} Result.make (0)
 		end
-		
+
 	recent_nodes (a_lower: INTEGER; a_count: INTEGER): LIST [CMS_NODE]
 			-- List of the `a_count' most recent nodes, starting from `a_lower'.
 		do