A round of fixes to merged Havoc/Eugene pickling

This is mostly re-applying Eugene's changes to the
tree on top of my changes. In this round specifically:

 - replace TypeInfo with AppliedType
 - uncomment the picklers for throwable and JsonValue
 - change JsonValue to use jawn/json4s
 - fill out the Values.scala picklers that were still ???
 - partially uncomment DynamicSerialization.registerSerializers