add router node
add tests
clean up failure scenarios
extend context to use map string object instead of map string string
Merge branch 'master' of github.com:metamx/druid into better-context
replace png with pdf graphics
include final license and DOI link
final sigmod version
more logging at initialization
Merge branch 'master' of github.com:metamx/druid
Merge pull request #436 from metamx/better-context

Extend context to able to take more sophisticated objects than just strings
Merge branch 'master' into router-node
minor layout/wording changes to make it fit nicely
address code review comments
Merge pull request #433 from metamx/router-node

Client-side tier-aware query runner