add some rights on assignee to the validated state on egov_universal_workflow. This avoid a security error if an agent have an assigned application and refuse it (it will change the state of the application to validated and redirect the agent on it).

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@24195 20353a03-c40f-0410-a6d1-a30d3c3de9de