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

Tools/Scripts/webkitpy/layout_tests/run_webkit_tests_unittest.py

Index: Tools/Scripts/webkitpy/layout_tests/run_webkit_tests_unittest.py
diff --git a/Tools/Scripts/webkitpy/layout_tests/run_webkit_tests_unittest.py b/Tools/Scripts/webkitpy/layout_tests/run_webkit_tests_unittest.py
index c3bf4c7c34ff85cc94f957281dae8717aa129795..7e0aa4da1c508e02c5b08d2fbf341e98850db15d 100644
--- a/Tools/Scripts/webkitpy/layout_tests/run_webkit_tests_unittest.py
+++ b/Tools/Scripts/webkitpy/layout_tests/run_webkit_tests_unittest.py
@@ -28,19 +28,19 @@
 # (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 Queue
+import StringIO
 import codecs
 import json
 import logging
 import os
 import platform
-import Queue
 import re
-import StringIO
 import sys
 import thread
 import time
 import threading
-import webkitpy.thirdparty.unittest2 as unittest
+import unittest
 
 from webkitpy.common.system import outputcapture, path
 from webkitpy.common.system.crashlogs_unittest import make_mock_crash_report_darwin