Remove thirdparty/unittest2 from webkitpy and require python2.7.

Tools/Scripts/webkitpy/tool/bot/commitannouncer_unittest.py

 # Copyright (C) 2013 Google Inc. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #    * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
 #    * Redistributions in binary form must reproduce the above
 # copyright notice, this list of conditions and the following disclaimer
 # in the documentation and/or other materials provided with the
 # distribution.
 #
 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-import webkitpy.thirdparty.unittest2 as unittest
+import unittest
 
 from webkitpy.tool.bot.commitannouncer import CommitAnnouncer
 from webkitpy.tool.mocktool import MockTool
 
 
 class CommitAnnouncerTest(unittest.TestCase):
     def test_format_commit(self):
         tool = MockTool()
         bot = CommitAnnouncer(tool, "test_password")
         self.assertEqual(
@@ skipping 158 matching lines @@
 
 Review URL: https://codereview.chromium.org/123456
 
 git-svn-id: svn://svn.chromium.org/blink/trunk@456789 bbb929c8-8fbe-4397-9dbb-9b2b20218538
 """))
 
     def test_sanitize_string(self):
         bot = CommitAnnouncer(MockTool(), "test_password")
         self.assertEqual('normal ascii', bot._sanitize_string('normal ascii'))
         self.assertEqual('uni\\u0441ode!', bot._sanitize_string(u'uni\u0441ode!'))