Archetype must provide siteuser, sitegroup and permissions

The archetype should bootstrap the siteuser and sitegroup and set the correct permission for reading and writing the forms. This is now a manual step for every single install and people use the admin user by default which is clearly wrong. This also leads to broken permissions settings on deployments, usually for forms:

03.06.2011 12:42:01 WARN [org.hippoecm.hst.core.container.HstComponentInvokerImpl.invokeAction():78] Component exception caught on window content with component com.onehippo.thiememeulenhoff.components.MyFormComponent: org.hippoecm.hst.core.component.HstComponentException: RepositoryException during storing form data