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

Tools/Scripts/webkitpy/common/system/zipfileset_unittest.py

 # Copyright (C) 2010 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:
 #
 # 1.  Redistributions of source code must retain the above copyright
 #     notice, this list of conditions and the following disclaimer.
 # 2.  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 APPLE AND ITS 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 APPLE OR ITS 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
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 # THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 import shutil
 import tempfile
-import webkitpy.thirdparty.unittest2 as unittest
+import unittest
 import zipfile
 
 from webkitpy.common.system.filesystem_mock import MockFileSystem
 from webkitpy.common.system.zipfileset import ZipFileSet
 
 
 class FakeZip(object):
     def __init__(self, filesystem):
         self._filesystem = filesystem
         self._files = {}
@@ skipping 48 matching lines @@
     def test_deep_extract(self):
         self._filesystem.maybe_make_directory('/some-dir')
         self._zip.extract('a/b/some-other-file', '/some-dir')
         self.assertTrue(self._filesystem.isfile('/some-dir/a/b/some-other-file'))
 
     def test_cant_delete(self):
         self.assertRaises(Exception, self._zip.delete, 'some-file')
 
     def test_namelist(self):
         self.assertTrue('some-file' in self._zip.namelist())