Schema migration of user ids

This commit requires a full db restoration from .sql file
For reasons I won't get into, I used a very poor primary key
for user accounts thinking I was being clever. I WAS NOT CLEVER!

    I KNOW BETTER THAN TO USE WEIRD PRIMARY KEYS
    I KNOW BETTER THAN TO USE WEIRD PRIMARY KEYS
    I KNOW BETTER THAN TO USE WEIRD PRIMARY KEYS

I've included a rudimentary migration test script, but for future
migrations I fully intend to use a proper migration tool. This
particular migration was just too tricky to do any other way.
Perfection paranoia (SQL databases drive me crazy)