fix rollup for hashed partitions

truncate timestamp while calculating the partitionNumber
Add test for bucket selection
Merge pull request #791 from metamx/fix-rollup-hashed-partitions

Fix rollup hashed partitions
New PartitionsSpec docs.
fix rabbit serde and add tests; fixes #794
address cr
Merge pull request #793 from metamx/partitions-docs

New PartitionsSpec docs.
one more comment
another test for defaults
fix more things
Merge pull request #795 from metamx/fix-rabbit

Fix rabbit serde and add tests; fixes #794
fixed broken internal link
added syntax highlighting
removed link with no target
javacript tiered broker selector strategy
add documentation
fix ordering for partitions with same start time, fixes #796

Partitions with same start time may produce results out of order,
           especially in the presence of data gaps.

Results for those segments must be re-ordered prior to being merged
fix serde
Merge pull request #799 from metamx/js-tiered-broker-selector

JavaScript tiered broker selector
make it work with Java 8