Add a partition method to RichPipe.
Rough outline of a partition job test.
Fix partition test.
Change partition to take a generic function from A->R, not just a predicate function.
Field -> Fields
Add arity match assert and discard tmp fields.
Fix PartitionJob test by specifying the order of the output fields.
Merge pull request #246 from arkajit/partition

Create a Partition method for RichPipe.