Trivial initial migration to set up a badge table with almost no fields
Adds badge model and basic test, with refactoring out of test helpers
Remove hardcoded config from migrations module
Remove UNIQUE constraint until we're sure we need it, as it's easier to add later than remove
Merge pull request #45 from stenington/initial-migration

Trivial initial migration to set up a badge table with almost no fields, and model with no extra methods