Proposed Fix for issue #668

Commit messages are hopefully self explanatory.

This allows the handy conversion to `List<T>` for Gherkin tables to work from the Scala DSL.  See the new Scenario and custom object "Cuke" added to the test suite for an example using a Scala class wrapped in a `java.util.List<Cuke>`.

Ideally I'd like to support scala Lists, but that can wait for a later enhancement.