Add support for Long metric

Add support for Long metric
Merge pull request #17 from druid-io/long-metric

Add support for Long metric
fix-rollup for hash based partitionsSpec
Merge pull request #23 from druid-io/fix-rollup

fix-rollup for hash based partitionsSpec
[maven-release-plugin] prepare release druid-api-0.2.16
[maven-release-plugin] prepare for next development iteration
allow for a default property value in PolyBind
Merge pull request #26 from druid-io/default-property-polybind

allow for a default property value in PolyBind
[maven-release-plugin] prepare release druid-api-0.2.17
[maven-release-plugin] prepare for next development iteration
Merge branch 'master' into remove-backwards-compatibility