Google CodeRetreat final iteration solution with unit tests

Some of the iterative tasks:

1. Unit Testing - want()..got()
2. Last minute requirement changes
3. Pair programming
4. Intent and testability
5. Ping pong programming
6. Commenting and interfaces
7. ABBA programming
8. Modularity and functional approach
9. One function doing one thing and doing it fast
10. Fast 2.30 minutes switches and git commit, git reset —hard