Add copyright information to .py files

This change adds explicit copyright information too python
files files.  The copyright year used in each case is the
date of the first git commit of each file.

The goal is to allow jsoncpp to be integrated into the
chromium source tree which requires license information in
each source file.

fixes #234
diff --git a/test/cleantests.py b/test/cleantests.py
index 1a4f1f1..9772d54 100644
--- a/test/cleantests.py
+++ b/test/cleantests.py
@@ -1,4 +1,10 @@
-# removes all files created during testing
+# Copyright 2007 Baptiste Lepilleur
+# Distributed under MIT license, or public domain if desired and
+# recognized in your jurisdiction.
+# See file LICENSE for detail or copy at http://jsoncpp.sourceforge.net/LICENSE
+
+"""Removes all files created during testing."""
+
 import glob
 import os