ALL WORKSHOPS - auto-assign student numbers dynamically

[mshoger]

One of the constant conundrums of workshops is pre-assigning student ID's, then half of them don't show and you have to scramble to get number reassigned to your waitlisters.

Perhaps we could make something link https://github.com/Crosbie/username-distribution part of the workshops so that as students join the session, they are directed to register for a student ID number and are then provided all of the pertinent info.