[FIX] Bug 267: wsdl fails with "Argument is out of range."

This fix bug 267
https://bugzilla.xamarin.com/show_bug.cgi?id=267

Signed-off-by: Etienne CHAMPETIER <etienne.champetier@fiducial.net>
Merge pull request #762 from echampet/wsdl

[FIX] Bug 267: wsdl fails with "Argument is out of range."