Create default properties under noupdate data tag

The default properties should be modifiable by the user.

issue5957
review26821002

configuration.xml

@@ -21,7 +21,8 @@ this repository contains the full copyright notices and license terms. -->
         <menuitem parent="menu_configuration"
             action="act_purchase_configuration_form"
             id="menu_purchase_configuration" icon="tryton-list"/>
-
+    </data>
+    <data noupdate="1">
         <record model="ir.property" id="property_purchase_sequence">
             <field name="field"
                 search="[('model.model', '=', 'purchase.configuration'), ('name', '=', 'purchase_sequence')]"/>