First pass at schema.
Add lib/db.js [from mozilla/badgekit-api]
Model files
Add `createdOn` for all tables.
Add `createdOn` to models; enforce referential integrity
Add package.json, .gitignore
Create test harness; start testing models.
Test fixtures.
Test cascading delete.
Add sanity tests for rest of models.
Attach metadata to earner via constructor.
Merge pull request #4 from mozilla/models

Models