Druid Fireshose

Add druidFirehose, can be used to reIndex filtered data from a
datasource
review comments

1) Rename firehose to IngestSegment
2) fix segment overlapping, intervals
3) fix overshadow
CombiningFirehoseFactory

can be used to ingest data from multiple sources.
Use Ingest task instead of Noop Task
improve memory usage and rename firehose
rejiggering the cache for groupBy and select
Merge branch 'master' into rejigger-cache

Conflicts:
	pom.xml
address code review comments
fix #636
update README
minor fixes

fix IndexOutOfBoundsException
fix ingestFirehose
disable middlemanagers based on worker version
Merge pull request #627 from metamx/druid-firehose

Functionality to ingest a Druid segment and change the schema
some minor cleanups to ingest firehose
address code review
update pom and fix broken UT
fix doc
Merge pull request #638 from metamx/rejigger-cache

Rejiggering the cache
Merge branch 'master' of github.com:metamx/druid into cleanup-ingest
fix broken UT