#1 calling web service without input or output defined

[Sérgio Fernandes]

This causes a NullPointerException when WebServiceActivity
class assumes that Input and Output Message are defined and
tries to resolve them. Haven't checked whether it's really a big
bug or simply the WSDL described the operation as having I/O
and the class assumes there had to be something.

Either way, we should react better that a NullPointerException to
this. How? I don't know yet.