Initial JUnit test
Remove unnecessary casting
Make DaytimePeakPerioud methods static and unit test
Clean up setter methods for Bill object
Clean up some of the test files
Initial BillingSystem Unit tests
Mock cleanups
Implement tests for Billing System
Remove MockTariffDatabase because it was not useful
Merge pull request #3 from rmbennett/original-tests

Unit Tests for Original Behaviour [WIP]