[FIX] fields: apply user timezone in display name for models using a datetime as name

For models using a datetime field as name (hr.attendance for instance), the user timezone wasn't applied in the display name.
Therefore, in the breadcrumb, the datetime was different than in the form if the user had another timezone than UTC.

openerp/osv/fields.py

@@ -367,6 +367,11 @@ class datetime(_column):
                               exc_info=True)
         return utc_timestamp
 
+    @classmethod
+    def _as_display_name(cls, field, cr, uid, obj, value, context=None):
+        value = datetime.context_timestamp(cr, uid, DT.datetime.strptime(value, tools.DEFAULT_SERVER_DATETIME_FORMAT), context=context)
+        return tools.ustr(value.strftime(tools.DEFAULT_SERVER_DATETIME_FORMAT))
+
 class binary(_column):
     _type = 'binary'
     _symbol_c = '%s'