Add number of skipped testcases

based on @munkyu's pull request #130.

Author: dnozay

xmlrunner/result.py

@@ -343,6 +343,9 @@ def _report_testsuite(suite_name, tests, xml_document, parentElement,
         errors = filter(lambda e: e.outcome == e.ERROR, tests)
         testsuite.setAttribute('errors', str(len(list(errors))))
 
+        skips = filter(lambda e: e.outcome == _TestInfo.SKIP, tests)
+        testsuite.setAttribute('skipped', str(len(list(skips))))
+ 
         _XMLTestResult._report_testsuite_properties(
             testsuite, xml_document, properties)