Extend Camp object with an optional "Call for Volunteers" #1940
Description
It would be useful to extend the Camp objects with a "Call for Volunteers" field that can be null. When the field is non-null, it could be displayed as a "Volunteering" tab in the main camp menu (next to "Program" (with the CFP in) and "Sponsors" (with the Call for Sponsors in)). When it's null, just ignore showing anything since we won't add this back in time for previous camps.
It would be useful to have the content be passed through our markdown formatter.