Juwang - round trip test with class hierarchy

RoudTripTest today test a complex object with a newly build configuration and serialized/deserialized configuration. But it doesn't leverage  deserailizaed class hierarchy when deserialize the configuration. 

In a real client 's scenario, we have serialized class hierarchy and Task configuration,  then we need to deserialize the configuration with the deserialized class hierarchy.  This scenario now is covered in the RoundTripTests. 

This is to resolve issue #200.
We should delete the file at the end of the test. That is also true for the old test, of course.