Add support for honorary members and alumni members
This fixes issues #4 (closed) and #5 (closed). Honorary members are people who we're recognizing have done something helpful to us, alums are people who graduated in good standing with us. Basically, this lets these people contribute, but they may not hold office, run for anything, get access to important services, or be counted as "members" when we're doing membership totals (to make the RSO people happy).