Bug 1023935 - Use 'mozrunner-startup' instead of 'automation' as the test name during startup; r=ahal

Until we run the first test, we set self.last_test to a dummy value,
so if we time out, we'll end up with a vaguely understandable error:
TEST-UNEXPECTED-FAIL | <test_name> | application timed out after 330.0 seconds with no output

This makes the test name slightly more unique, so as to make TBPL's
matching against bugs less prone to false positives.

testing/mozbase/mozrunner/mozrunner/base/runner.py

@@ -20,7 +20,7 @@ class BaseRunner(object):
     The base runner class for all mozrunner objects, both local and remote.
     """
     __metaclass__ = ABCMeta
-    last_test = 'automation'
+    last_test = 'mozrunner-startup'
     process_handler = None
     timeout = None
     output_timeout = None