Create a "forked JVM" test framework

[earldouglas]

The current unit tests rely on the InMemTest class, which is a bit of a hack to simulate continuation serialization transport.

It would be much better to create a test framework which can be run as a usual unit test (i.e. with sbt test) that kicks off two real InetTransporter.listen threads (on different local ports) and tests actual serialization and transportation over sockets.

This might be doable with some advanced sbt trickery, or within a class via some clever class loading.

[earldouglas]

See the Akka multi-JVM testing module: https://github.com/typesafehub/sbt-multi-jvm