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

Tools/Scripts/webkitpy/layout_tests/servers/crash_service_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
@@ skipping 10 matching lines @@
 # 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
 # (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 re
 import sys
-import webkitpy.thirdparty.unittest2 as unittest
+import unittest
 
 from webkitpy.common.host_mock import MockHost
 from webkitpy.layout_tests.port import test
 from webkitpy.layout_tests.servers.crash_service import CrashService
 from webkitpy.layout_tests.servers.server_base import ServerError
 
 
 class TestCrashService(unittest.TestCase):
     def test_start_cmd(self):
         # Fails on win - see https://bugs.webkit.org/show_bug.cgi?id=84726
@@ skipping 29 matching lines @@
 
         def mock_returns(return_values):
             def return_value_thunk(*args, **kwargs):
                 return return_values.pop(0)
             return return_value_thunk
 
         host.executive.check_running_pid = mock_returns([True, False])
         server._wait_for_action = wait_for_action
 
         server.stop()