com.twitter.tormenta
* Need to create our own Externalizer to avoid calling chill Externalizer that uses setReferences, which creates a Kryo version conflict (see https://github.com/twitter/chill/issues/173).
* Need to create our own Externalizer to avoid calling chill Externalizer that uses setReferences, which creates a Kryo version conflict (see https://github.com/twitter/chill/issues/173).