Allow ability to turn off automatic "promotion" to provided user

FYI: I believe the scenario you describe is not possible to do anymore because of where this roster removal is blocked. Sounds related.

If you don't turn off automatic promotion, and follow this procedure, experience is bad. This isn't just an edge case to me, seems like a bigger problem, surprised no one else has run into this.

create a site as an instructor, then remove the roster from the site. The instructor is removed from the site and gets "Site Unavaiable". So if say you create a site, realize you picked the wrong roster, then deleted the the roster before adding a new, suddenly you loose access to your site. That would really suck if say you had put a bunch of content in the site already.

Applied in r77620, thanks for the patch.

If this patch is applied with no change to sakai.properties, then no current functionality changes.

If you configure:

promoteUsersToProvided@org.sakaiproject.authz.api.AuthzGroupService=false

into sakai.properties, then functionality will return to how it was before .

As it's a somewhat actual case, I think the bean-value property is probably most consistent with previous practice, e.g. a name/value property in kernel-component/src/main/webapp/WEB-INF/authz-components.xml and settable in sakai.properties as

promoteUsersToProvided@org.sakaiproject.authz.api.AuthzGroupService=true

or similar.