+ move aggregated value to the center of time interval where it was aggregated
 * DurationLogProcessor
 * MetricLogProcessor
 * MonitoringAggregator
+ replace ExtendedIntervalAggregator with AtomicLong
Merge pull request #410 from amikryukov/jfg-600-pull

JFG-600 move aggregated value to the center of time interval where it was aggregated