Added revisions support to node management.

Updated node extension implementation.
Updated known permissions for node module.
Improved code for node storage extension , in preparation to code factorization.
Ensured that author is updated when saved.

modules/node/persistence/cms_node_storage_extension.e

@@ -6,8 +6,17 @@ note
 deferred class
 	CMS_NODE_STORAGE_EXTENSION [G -> CMS_NODE]
 
+feature -- Change
+
+	set_node_api (a_node_api: CMS_NODE_API)
+		do
+			node_api := a_node_api
+		end
+
 feature -- Access
 
+	node_api: CMS_NODE_API
+
 	content_type: READABLE_STRING_8
 		deferred
 		end