Add CamusSweeperETLPartitionPlanner

The idea is to use default partitioning schema (yyyy/mm/dd/HH) for
events offloaded from Kafka. Then reprocess this dump for each portal
individually. We need ETL partition planner for that (will run in hourly
sweeper) which will transform files in ETLed directory to
hive-compatible directories.

Also: sweepers will now only include records for specific portal
(condition in map task). This is necessary because data files in ETLed
directory contains data for all portals.
Merge pull request #14 from vinted/features/per-portal-sweeper

Generate less small Avro files while offloading