defect 4283: add note head of the subtourines (in hosts.pm) which called in ddns.pm. Generally xcat does not suggest that call subroutine of xcat_plugin from antoher xcat_plugin module, but since the change would be big, I add this note head the subroutines as a notification for the member who would change the involved subroutines.
fix bug 4305:error info :Unknown arch during ubuntu 14.04.01 osimage nodeset on p8le env