add router node
add tests
clean up failure scenarios
extend context to use map string object instead of map string string
fix serialisation of segmentMetaDataQuery
Merge pull request #437 from metamx/segmentmetadataquery-fix

fix serialisation of segmentMetaDataQuery
Merge branch 'master' of github.com:metamx/druid into better-context
prepare for next release
[maven-release-plugin] prepare release druid-0.6.73
[maven-release-plugin] prepare for next development iteration
fix typos
update document class for sigmod
update makefile to create sigmod zip file
add keywords
copyright placeholder
updated pdf
Update index.md

Fixed a few typos and grammatical issues.
replace png with pdf graphics
include final license and DOI link
final sigmod version