Implemented CMS storage for user and nodes.

Implemented role and permission storage.
Introduced the CMS_PARTIAL_NODE and CMS_PARTIAL_USER.
Added support for node storage extension
  - storage of data specific to each node content type,
  - in addition to the core CMS_NODE)
  - For now, only implemented for SQL storage.
Note: in current version, CMS_PAGE support is hard coded in the core,
    (as opposed to be only supported by the node module.)
Commented/removed for now, the Web API code to update node summary, title, via REST request.

src/persistence/cms_storage_null.e

@@ -95,12 +95,20 @@ feature -- Change: user
 		do
 		end
 
+
 feature -- Access: roles and permissions
 
 	user_role_by_id (a_id: like {CMS_USER_ROLE}.id): detachable CMS_USER_ROLE
 		do
 		end
 
+	user_roles_for (a_user: CMS_USER): LIST [CMS_USER_ROLE]
+			-- User roles for user `a_user'.
+			-- Note: anonymous and authenticated roles are not included.
+		do
+			create {ARRAYED_LIST [CMS_USER_ROLE]} Result.make (0)
+		end
+
 	user_roles: LIST [CMS_USER_ROLE]
 		do
 			create {ARRAYED_LIST [CMS_USER_ROLE]} Result.make (0)
@@ -179,4 +187,13 @@ feature -- Node
 		do
 		end
 
+
+feature -- Helpers
+
+	fill_node (a_node: CMS_NODE)
+			-- Fill `a_node' with extra information from database.
+			-- i.e: specific to each content type data.
+		do
+		end
+
 end