Fix import of some autotest cros modules, make them callable outside of autotest runtime.

client/cros/dns_server.py

Index: client/cros/dns_server.py
diff --git a/client/cros/dns_server.py b/client/cros/dns_server.py
index 8ce2ad01c5158060a4349488ec2d248968b26d0a..7deb4ea73a85c08cc3fa37964ad04ee5af0d1cf9 100644
--- a/client/cros/dns_server.py
+++ b/client/cros/dns_server.py
@@ -2,7 +2,8 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-import logging, threading, time, utils
+import logging, threading, time
+from autotest_lib.client.bin import utils
 
 class LocalDns(object):
     """a wrapper around miniFakeDns that handles managing running the server