Fix partitioned seq int gen leaving some keys out

Fixes #75
For example, with 12 workers and 100 keys, it leaves the 4 last keys out
(100 rem 12).  This makes those keys (at most # of workers) be given to
the last worker.
Merge pull request #76 from basho/eas-fix-remainder-partitioned-seq-int

Fix partitioned seq int gen leaving some keys out