Take advantage of the Model inheritance provided by polymodel.PolyModel to
have create a class hierarchy rooted at Person.
Also, add some missing Role classes, such as Role, (Organization) Mentor,
(Club) Member, (School) Student. Make (Organization) Administrator be a
Reviewer like Mentor is.
Patch by: Todd Larsen
Review by: Pawel Solyga, Sverre Rabbelier, Augie Fackler
Review URL: http://codereviews.googleopensourceprograms.com/607
A list of bugs is available in the Google App Engine SDK project on Google Code.
Please visit http://code.google.com/p/googleappengine for more details.