Remove Copyright from every source file

Replace it by website link; copyright appears in the LICENSE file already, which is sufficient
diff --git a/examples/rewrite_ast.py b/examples/rewrite_ast.py
index 289e26f..7d1b196 100644
--- a/examples/rewrite_ast.py
+++ b/examples/rewrite_ast.py
@@ -3,7 +3,7 @@
 #
 # Tiny example of rewriting a AST node
 #
-# Copyright (C) 2014, Akira Hayakawa
+# Eli Bendersky [http://eli.thegreenplace.net]
 # License: BSD
 #-----------------------------------------------------------------
 from __future__ import print_function