* Translation functions from hash (integer or binary) to partition ID
  and back. Partition IDs are zero-based up to (but not including) ring
  size.
* For user-facing tools, hash_is_partition_boundary/2 can be used to
  verify whether a hash provided by the user is actually the first
  in a partition.
* EQC and unit tests.
Switch to ordsets to prop_only_boundaries faster. Also allow test to run longer to cover more hash space
Make EQC tests easier to scan
Leverage equals/2 per @seancribbs
Merge pull request #638 from basho/feature/jrd/partition-ids-integrated

Introduce partition IDs

Reviewed-by: JeetKunDoug