- minor refactoring in DefaultArchiver and SizeAndTimeBasedArchiveRemover

- Adapted TimeBasedRollingWithArchiveRemovalTest so that
dailySizeBasedRollover() no longer fails under certain circumstances,
e.g. when in the last period no size-based rollover occuers. Also
increased the number of ticks per period (more logging calls) and
increased the triggering size (less size-based rollovers for faster
test execution time)