Fix local hashJoin bug
use typed-API in cross, not crossWithTiny
Remove one unneed lambda
Add leftCross/cross for Avi
remove code duplication is cross
Merge pull request #768 from twitter/fixhashjoinbug

Fix local hashJoin bug
Avoid using Iterable/Lists when an Iterator will do
Merge pull request #769 from twitter/flatmapfn

Avoid using Iterable/Lists when an Iterator will do