Change #! line to modern usage; also chmod +x

Demo/zlib/minigzip.py

@@ -1,4 +1,4 @@
-#!/usr/local/bin/python
+#!/usr/bin/env python
 # Demo program for zlib; it compresses or decompresses files, but *doesn't*
 # delete the original.  This doesn't support all of gzip's options.
 

Demo/zlib/zlibdemo.py

@@ -1,4 +1,4 @@
-#!/usr/local/bin/python
+#!/usr/bin/env python
 
 import zlib, sys
 if len(sys.argv)>1: filename=sys.argv[1]