Refactor au_test_harness into modules and refactor to use worker design.

bin/au_test_harness/update_exception.py

Index: bin/au_test_harness/update_exception.py
diff --git a/bin/au_test_harness/update_exception.py b/bin/au_test_harness/update_exception.py
new file mode 100644
index 0000000000000000000000000000000000000000..4c1e73ec64641a23a6bc3d63e99a3d74794615dc
--- /dev/null
+++ b/bin/au_test_harness/update_exception.py
@@ -0,0 +1,11 @@
+# Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""Module containing update exceptions."""
+
+class UpdateException(Exception):
+  """Exception thrown when _UpdateImage or _UpdateUsingPayload fail"""
+  def __init__(self, code, stdout):
+    self.code = code
+    self.stdout = stdout