Upgrade to Hadoop 2.3.0
Merge branch 'master' into hadoop-version-update
upgrade default version in CluHadoopIndexer and merge from master
update default version in docs
Support for postgresql

I think it was the last request using 'end' missing the postgresql support.
overhaul of config reference, first pass
fix NPE in aggregatrFirstTopnAlgo
review comments
cleanup code in router and add forwarding for get requests
use a separate annotation for the router, less confusing
avoid copying bytes
throw ISE when no servers found at all
Merge pull request #484 from metamx/fix-router

Cleanup code in router and add forwarding for get requests
point code docs to latest instead of a version
Major edits including the following:

* Emitter module is logging
* readTimeout for http client module 15min
* Fixed broken link to ZooKeeper.html
* Clarified druid.processing.numThreads is #cores - 1 or 1 if #cores == 1
* aws storage section moved under deep storage
* Added more info on various monitors and how to specify them (Metrics Module section)
* Clarified info on:
    * storage tiers and added the property druid.server.priority (Storage Node Module section)
    * segment cache : where historical nodes store data in disk cache
    * druid.query.chunkPeriod
* Removed druid.db.connector.pollDuration
* Fixed definition of druid.selectors.indexing.serviceName and moved to discovery section
Merge pull request #483 from metamx/fix-aggregatefirst-topn-algo

fix NPE in aggregatrFirstTopnAlgo
minor edit to Metrics Module section
Merge branch 'master' into igalDruid
prepare for next release
[maven-release-plugin] prepare release druid-0.6.91