Support for postgresql

I think it was the last request using 'end' missing the postgresql support.
Fix typo in link back to The Druid Cluster page.
fix by segment results

1) fix class cast in by segment results
2) exclude old netty version coming from curator
merge changes from master
Merge pull request #494 from metamx/fix-bysegment-results

fix bySegmentResults
Merge pull request #493 from phungleson/fix-link-typo

Fix typo in the link back to The Druid Cluster page.
prepare for next release
[maven-release-plugin] prepare release druid-0.6.96
[maven-release-plugin] prepare for next development iteration
clean up topnbinaryfn
fix npe in topNBinaryFn with post aggs
Merge pull request #496 from metamx/fix-topN-postagg-npe

fix npe in topNBinaryFn with post aggs
[maven-release-plugin] prepare release druid-0.6.97
[maven-release-plugin] prepare for next development iteration
update versions
[maven-release-plugin] prepare release druid-0.6.98
[maven-release-plugin] prepare for next development iteration
Revert "fix npe in topNBinaryFn with post aggs"

This reverts commit bbedde3418ba0a83a1777681d549b3ff1295b000.
calculate postAggs while pulling from cache
fix more issues and add test

1) Add test for caching and calculation of dependent post-aggs for
TimeSeries and TopN
2) Fix more NPEs while calculating dependent postAggs, passing
baseHolder was wrong as it does not contain post-aggs during computing
dependent ones.