Hide "core faculty" setting for sites that are not using it

Hide "core faculty" setting for sites that are not using it

Since we released the core faculty feature early this year, many people have been setting it reflexively. Now that option will only appear if the site manager has chosen to use core faculty on the site. When associating people with sites, editors will not see the "core faculty" checkbox for sites which do not have this setting.

Even if a site does not have core faculty associated, the core faculty checkbox will still appear when editing the affiliation of a person who was set as core faculty prior to this release. This will allow site editors to correct the person's association by unchecking the box.