Merge: nitunit: improve generated XML

The XML format used by Jenkins is under-specified. So after loosely googling and a lot of trials and errors here is some improvement of the XML that enhance the user experience on Jenkins.

To experiment, I used a false job to see the results of nitunit for the test cases in tests (where a lot are expected to fails)

* the (ANSI-colored) log: http://gresil.org/jenkins/job/ZZnothing/195/console
* the results: http://gresil.org/jenkins/job/ZZnothing/195/testReport/

The main improvements are:

* messages are open by default (when you click on the + of a failed tests)
* add a time (not impressive but might be useful on real tests)
* all test cases are counted
* more readable names. Compare with http://gresil.org/jenkins/job/ZZnothing/189/testReport/ for instance

Pull-Request: #2182
Reviewed-by: Alexandre Terrasa <alexandre@moz-code.org>