Start investigating moving to iterators for python API like the Java/Scala one. tl;dr: We will have to write our own iterator since the default one doesn't pickle well
Try and make pickling list iterators work
Revert "Try and make pickling list iterators work"

This reverts commit f607138dfea8f04d7b302f49b76dba8756b17575.
Python tests now pass with iterator pandas