bugs:
 - ChunkedResults returns only the first chunk
 - wrong config paths in HttpQueryServer
 - unused config path in KafkaPointsConsumerConfig
 changes:
 - informative error message on wrong sink and source types
 - some configs moved to defaults
simple health-checking handle
kafka consumer test fixed
Merge pull request #41 from VasilyKolpakov/health-check-server

Health check server