kafka08 simple consumer firehose

I also changed druid-api package, added a method "public long getLastOffsetCommitTime(); " in "interface Firehose". The  way to call new commit method is hacked by using reflection,  quick and dirty way, need to refactor to add some method to interface. 
You are breaking the semantics of the Firehose here.  the nextRow() call is never supposed to block.  If blocking is required, it should happen in the hasMore() call.