More translator stubs, plus refactoring.

Add more translators stubs, move pattern matching on NeutronOp into
base NeutronTranslator trait, and move all translators into
translators package.

Change-Id: Ib3c4cddf3c58389615d3b97860f94ff987b1c9bc
Signed-off-by: Brandon Berg <bberg@midokura.com>
Merge "More translator stubs, plus refactoring."