add unique-constraint to registrant_event_sign_ups to prevent multiple-rows problem
add unique-constraint to registrant_event_sign_ups to prevent multiple-rows problem

scotthue/unicycling-registration,rdunlop/unicycling-registration,rdunlop/unicycling-registration,rdunlop/unicycling-registration,rdunlop/unicycling-registration,scotthue/unicycling-registration,scotthue/unicycling-registration