Improve junit xml generated fields

* trial ('testsuites' node): Add fields 'tests', 'errors', 'failures',
  'time'.
* testsuite: Add fields 'errors', 'failures', 'skipped',
  'disabled'
* test: Add field 'classname' (empty).

Fix and improve suite.py and test.py to count errors, skipped, failures
properly.

Change-Id: Ie2d10cee88a9c0d829e4620553164cf3150e8e5c
diff --git a/src/osmo_gsm_tester/suite.py b/src/osmo_gsm_tester/suite.py
index c2faa36..8c79d35 100644
--- a/src/osmo_gsm_tester/suite.py
+++ b/src/osmo_gsm_tester/suite.py
@@ -213,9 +213,9 @@
             util.import_path_remove(suite_libdir)
             self.duration = time.time() - self.start_timestamp
 
-            passed, skipped, failed = self.count_test_results()
+            passed, skipped, failed, errors = self.count_test_results()
             # if no tests ran, count it as failure
-            if passed and not failed:
+            if passed and not failed and not errors:
                 self.status = SuiteRun.PASS
             else:
                 self.status = SuiteRun.FAIL
@@ -229,14 +229,17 @@
         passed = 0
         skipped = 0
         failed = 0
+        errors = 0
         for t in self.tests:
-            if t.status == test.Test.PASS:
+            if t.status == test.Test.SKIP:
+                skipped += 1
+            elif t.status == test.Test.PASS:
                 passed += 1
             elif t.status == test.Test.FAIL:
                 failed += 1
-            else:
-                skipped += 1
-        return (passed, skipped, failed)
+            else: # error, could not run
+                errors += 1
+        return (passed, skipped, failed, errors)
 
     def remember_to_stop(self, process, respawn=False):
         '''Ask suite to monitor and manage lifecycle of the Process object. If a