Test time entry start/stop/duration business logic.
Remove obsolete TODO comment.
Change properties used for testing.

The Duration and RawDuration properties will be removed in the refactor,
making sure that the AttributeLookupCacheTests would still work.
Remove live duration.

Removes live durations and duration property.
Add ToUnix DateTime extension method.
Migrate Joey to new TimeEntryModel behaviour.
Hide non-active projects from available list.
Merge branch 'roosmaa-te-biz'

Closes #53
Closes #44