Implemented view node by content type (no more hardcoded cases).

Added CMS_NODE_TYPE as descendant of CMS_CONTENT_TYPE,
  in case we have content which is not a node in the future.
  (probably useless, but for now, this extra abstraction is harmful)
Moved all node related code under node module cluster.
Applied comments from Javier Velilla.
Code cleaning.

src/service/cms_module.e

@@ -0,0 +1,122 @@
+note
+	description: "Describe module features that adds one or more features to your web site."
+	date: "$Date: 2014-11-13 16:23:47 +0100 (jeu., 13 nov. 2014) $"
+	revision: "$Revision: 96085 $"
+
+deferred class
+	CMS_MODULE
+
+inherit
+	REFACTORING_HELPER
+
+feature -- Access
+
+	is_enabled: BOOLEAN
+			-- Is the module enabled?
+
+	name: STRING
+			-- Name of the module.
+
+	description: STRING
+			-- Description of the module.
+
+	package: STRING
+			--
+
+	version: STRING
+			-- Version od the module?
+
+feature {CMS_API} -- Module Initialization
+
+	initialize (api: CMS_API)
+			-- Initialize Current module with `api'.
+		require
+			is_enabled: is_enabled
+		do
+				-- Redefine to process specific module initialization.
+		end
+
+feature {CMS_API} -- Access: API
+
+	module_api: detachable CMS_MODULE_API
+			-- Eventual module api.
+
+feature {CMS_API} -- Module management
+
+	is_installed (api: CMS_API): BOOLEAN
+			-- Is Current module installed?
+		do
+			Result := is_enabled
+				-- FIXME: implement proper installation status.
+		end
+
+	install (api: CMS_API)
+		require
+			is_not_installed: not is_installed (api)
+		do
+				-- Not Yet Supported
+		end
+
+	uninstall (api: CMS_API)
+		require
+			is_installed: is_installed (api)
+		do
+				-- Not Yet Supported
+		end
+
+feature -- Router
+
+	router (a_api: CMS_API): WSF_ROUTER
+			-- Router configuration.
+		require
+			is_enabled: is_enabled
+		deferred
+		end
+
+feature -- Hooks configuration
+
+	register_hooks (a_response: CMS_RESPONSE)
+			-- Module hooks configuration.
+		require
+			is_enabled: is_enabled
+		do
+		end
+
+feature -- Filter
+
+	filters (a_api: CMS_API): detachable LIST [WSF_FILTER]
+			-- Optional list of filter for Current module.
+		require
+			is_enabled: is_enabled
+		do
+		end
+
+feature -- Settings
+
+	enable
+			-- enable the module.
+		do
+			is_enabled := True
+		ensure
+			module_enabled: is_enabled
+		end
+
+	disable
+			-- disable the module.
+		do
+			is_enabled := False
+		ensure
+			module_disbaled: not is_enabled
+		end
+
+feature -- Hooks
+
+	help_text (a_path: STRING): STRING
+		do
+			debug ("refactor_fixme")
+				to_implement ("Add the corresponing implementation.")
+			end
+			create Result.make_empty
+		end
+
+end