it is hard to distinguish an exception in recipe from an exception in recipe engine (recipe engine crash) by looking at a result protobuf message

I tried to fix this problem (https://codereview.chromium.org/2798053003), but tests fail and I am extremely ineffective in figuring out why, perhaps because i am unfamiliar with the code base; so making it available.

Until this is fixed, kitchen will treat recipe exceptions and recipe engine crashes the same.