Fix for running tests on Windows under Python 2.6

TODO:
* Track down the source of this error which occurs on OS X, Windows, and--presumably--Linux when running against Splunk 6.2 or 6.3 under Python 2.6;

    AttributeError: 'TestCookieAuthentication' object has no attribute 'assertIsNotNone'

* Test with Python 2.6 under Linux.

Author: David Noble

tests/testlib.py

@@ -259,6 +259,6 @@ def tearDown(self):
                 except HTTPError as error:
                     if not (os.name == 'nt' and error.status == 500):
                         raise
-                    print 'Ignoring failure to delete {} during tear down: {}'.format(appName, error)
+                    print 'Ignoring failure to delete {0} during tear down: {1}'.format(appName, error)
         if self.service.restart_required:
             self.clear_restart_message()