Fix md5sums for services (on-the-fly generation)

[chfritz]

As pointed out in #22, the md5sums for service classes generated by the on-the-fly code is currently wrong. The correct md5sum for a service is the md5sum of the concatenation of the request and the response md5 text -- which is the message text without a trailing new line. For instance, for SetBool, the text to use for md5 is:

bool databool success
string message

(Yes, there is no whitespace or new line between the two parts!).