devserver: module import cleanup

* Import statements re-grouped: standard lib, third party,
  project-local; separated by a single line, preceded by a single line
  and followed by two lines. Each group is sorted alphabetically.

* Removed unused imports.

BUG=None
TEST=Passes unit tests.

Change-Id: Iee4f78b1256457bd19b2c159a29763ba3404c272
Reviewed-on: https://gerrit.chromium.org/gerrit/33859
Reviewed-by: Chris Sosa <sosa@chromium.org>
Commit-Ready: Gilad Arnold <garnold@chromium.org>
Tested-by: Gilad Arnold <garnold@chromium.org>
diff --git a/update_test.py b/update_test.py
index bdd340b..2a52542 100755
--- a/update_test.py
+++ b/update_test.py
@@ -1,10 +1,14 @@
 #!/usr/bin/python
+#
+# Copyright (c) 2012 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.
 
-import urllib2
+from xml.dom import minidom
 import sys
 import threading
-from urlparse import urljoin
-from xml.dom import minidom
+import urllib2
+
 
 UPDATE_BLOB="""\
 <?xml version="1.0" encoding="UTF-8"?>