Fix the libinteractive serialization

* Due to Java's type erasure, Enumeration types were being lost so the
  libinteractive.target.Options object was not serialized.
* Path objects were not being serialized either.
* Lift was making serializing libinteractive.idl.IDL such a pain that it
  was much easier to ship the .idl source in the message and have the
  Runner deserialize it.
* Fixed #7