Improve texts in Dutch property files

In https://svn.hippocms.org/repos/hippo/hippo-cms7/cms/branches/hippo-cms-2.24.xx/workflow/frontend/src/main/java/org/hippoecm/frontend/plugins/standardworkflow/PermissionsFolderWorkflowPlugin_nl.properties and https://svn.hippocms.org/repos/hippo/hippo-cms7/cms/branches/hippo-cms-2.24.xx/workflow/frontend/src/main/java/org/hippoecm/frontend/plugins/standardworkflow/PermissionsFolderWorkflowPlugin%24PermissionsConfirmDialog_nl.properties are question marks in the translations, they need to be removed and 'toegestaande' should be 'toegestane'.