Bug 1247833 - Display the class name in mozunit output. r=gps

One can run individual tests with python testfile.py Class.method. But
the output for tests only shows the method so looking at a test output
is not enough to tell how to run one particular test. Moreover, there
are many cases where a test file contains multiple classes, and we fail
to identify the difference between those classes.

config/mozunit.py

@@ -33,9 +33,10 @@ class _MozTestResult(_TestResult):
             return str(test)
 
     def printStatus(self, status, test, message=''):
-        line = "{status} | {file} | {test}{sep}{message}".format(
+        line = "{status} | {file} | {klass}.{test}{sep}{message}".format(
             status=status,
             file=inspect.getfile(test.__class__),
+            klass=test.__class__.__name__,
             test=test._testMethodName,
             sep=', ' if message else '',
             message=message,