CA-137485: Updated XenModel with the new API bindings with serializable exceptions

Signed-off-by: Mihaela Stoica <mihaela.stoica@citrix.com>
CA-137485: Improvements to the Exception serialization unit tests

As per code review, wherever there is an 'if' in the unit tests there should be an assertion for the 'else' branch as well

Signed-off-by: Mihaela Stoica <mihaela.stoica@citrix.com>
Merge pull request #109 from MihaelaStoica/xs64bit

CA-137485: Updated XenModel with the new API bindings with serializable ...