Modify the output so that Jenkins XUnit plugin will parse it correctly

It seems that xunit performs some validations on the output XML with test results.

BTW I've found this schema 
https://svn.jenkins-ci.org/trunk/hudson/dtkit/dtkit-format/dtkit-junit-model/src/main/resources/com/thalesgroup/dtkit/junit/model/xsd/junit-4.xsd