fixed behavior on non-real time data points (clock differences,
queued or replayed data)
 * MAX_AGGREGATION_INTERVALS: consecutive number of extra aggregation
   buckets to keep, relative to most recent timestamp of previous data
   for that metric (and not system time)
 * MAX_AGGREGATION_AGE: maximum time (in number of aggregation intervals)
   to keep the buckets around (since system time of last update),
   defaults to 0 (no cleanup). Internally updated to
   MAX_AGGREGATION_INTERVALS if it is smaller that this setting.
 * do not write data that arrives to late (as it overwrites data that
   is stored), a warning is emitted to the aggregation log.

Conflicts:
	lib/carbon/conf.py

additional checkin to reset pull request

Fix typo introduced by 12c8a42d4d20785d82b49e8115f603dfc3beb788.

Fix error message formatting.

Fix whitespace.