Add a new 'format-webkitpy' command that will reformat code to the style guide.

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

Index: Tools/Scripts/webkitpy/common/system/executive_mock.py
diff --git a/Tools/Scripts/webkitpy/common/system/executive_mock.py b/Tools/Scripts/webkitpy/common/system/executive_mock.py
index 9989aace5df75d8e906f9d1ce092ab39586e0c7b..aa855d75d1391efe101348089f1123e2c2001015 100644
--- a/Tools/Scripts/webkitpy/common/system/executive_mock.py
+++ b/Tools/Scripts/webkitpy/common/system/executive_mock.py
@@ -168,6 +168,9 @@ class MockExecutive(object):
         self.calls.append(new_calls)
         return command_outputs
 
+    def map(self, thunk, arglist, processes=None):
+        return map(thunk, arglist)
+
 
 class MockExecutive2(MockExecutive):
     """MockExecutive2 is like MockExecutive except it doesn't log anything."""