Move libraries layout', model', `peristence' under cms folder

Updated code to the new layout.
Added missing comments.
Remove /example/api

cms/persistence/implementation/common/database/error/database_error.e

@@ -0,0 +1,23 @@
+note
+	description: "Error from database"
+	date: "$Date: 2013-08-08 16:39:49 -0300 (ju. 08 de ago. de 2013) $"
+	revision: "$Revision: 195 $"
+
+class
+	DATABASE_ERROR
+
+inherit
+	ERROR_CUSTOM
+
+create
+	make_from_message
+
+feature {NONE} -- Init
+
+	make_from_message (a_m: like message; a_code: like code)
+			-- Create from `a_m'
+		do
+			make (a_code, once "Database Error", a_m)
+		end
+
+end

cms/persistence/implementation/common/database/error/database_error_handler.e

@@ -0,0 +1,35 @@
+note
+	description: "Database error handler"
+	date: "$Date: 2013-08-08 16:39:49 -0300 (ju. 08 de ago. de 2013) $"
+	revision: "$Revision: 195 $"
+
+class
+	DATABASE_ERROR_HANDLER
+
+inherit
+	ERROR_HANDLER
+
+create
+	make
+
+feature -- Error operation
+
+	add_database_error (a_message: READABLE_STRING_32; a_code: INTEGER)
+			-- Add a database error.
+		local
+			l_error: DATABASE_ERROR
+		do
+			create l_error.make_from_message (a_message, a_code)
+			add_error (l_error)
+		end
+
+	add_database_no_change_error (a_message: READABLE_STRING_32; a_code: INTEGER)
+			-- Add a database error.
+		local
+			l_error: DATABASE_NO_CHANGE_ERROR
+		do
+			create l_error.make_from_message (a_message, a_code)
+			add_error (l_error)
+		end
+
+end

cms/persistence/implementation/common/database/error/database_no_change_error.e

@@ -0,0 +1,27 @@
+note
+	description: "Summary description for {DATABASE_NO_CHANGE_ERROR}."
+	author: ""
+	date: "$Date$"
+	revision: "$Revision$"
+
+class
+	DATABASE_NO_CHANGE_ERROR
+
+inherit
+	DATABASE_ERROR
+		redefine
+			make_from_message
+		end
+
+create
+	make_from_message
+
+feature {NONE} -- Init
+
+	make_from_message (a_m: like message; a_code: like code)
+			-- Create from `a_m'
+		do
+			make (a_code, once "Database No Change Error", a_m)
+		end
+
+end