custom slug

[hcientist]

Possibly related to #441 , I was going through the getting started docs (https://github.com/mozilla/openbadges-badgekit/wiki/BadgeKit-Self-Hosting-Guide) and i entered a custom value for the slug when inserting a system into the api db. I got a 404 when trying to create my first badge. chaning the slug to badgekit for my system seemed to fix the problem. perhaps I could have also fied it by chanigng the config for the web app to OPENBADGER_SYSTEM=myslug