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

Tools/Scripts/webkitpy/test/main_unittest.py

 # Copyright (C) 2012 Google, Inc.
 #
 # 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 INC. 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 INC. 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 StringIO
 import logging
 import sys
-import webkitpy.thirdparty.unittest2 as unittest
-import StringIO
+import unittest
 
 from webkitpy.common.system.filesystem import FileSystem
 from webkitpy.common.system.executive import Executive
 from webkitpy.common.system.outputcapture import OutputCapture
 from webkitpy.test.main import Tester
 
 
 STUBS_CLASS = __name__ + ".TestStubs"
 
 
@@ skipping 61 matching lines @@
                                 stdout=executive.PIPE, stderr=executive.PIPE)
             out, _ = proc.communicate()
             retcode = proc.returncode
             self.assertEqual(retcode, 0)
             self.assertIn('Cover', out)
         finally:
             if coverage_file_orig:
                 filesystem.move(coverage_file_orig, coverage_file)
             elif filesystem.exists(coverage_file):
                 filesystem.remove(coverage_file)