closes #1: view now displays all rates by using the currency of customer (default is EUR)
closes #2: added record merge modes and implemented the TimeRecord model to merge mutliple timesheets
closes #3: added record date to view
fixes #4: fixed time span calculation
closes #1: view now displays all rates by using the currency of customer (default is EUR) closes #2: added record merge modes and implemented the TimeRecord model to merge mutliple timesheets closes #3: added record date to view fixes #4: fixed time span calculation