Add JUnit XML reports; refactor test reporting

* Add Junit output file support
* Differentiate between an expected failure test and an error in the
test, as described in JUnit.
* In case of an error/exception during test, record and attach it to the
Test object and continue running the tests, and show it at the end
during the trial report.

Change-Id: Iedf6d912b3cce3333a187a4ac6d5c6b70fe9d5c5
diff --git a/suites/debug/fail.py b/suites/debug/fail.py
index 1b412b5..fcd56e0 100644
--- a/suites/debug/fail.py
+++ b/suites/debug/fail.py
@@ -2,4 +2,4 @@
 from osmo_gsm_tester.test import *
 
 # This can be used to verify that a test failure is reported properly.
-assert False
+test.set_fail('EpicFail', 'This failure is expected')