Fix chmod mode and add /usr/bin/python

This permits the script to be run by:
    cd compatibility/cdd
    ./make_cdd.py

Change-Id: I330fb479a5111f737b6adf772c2166c6afdd2f6d
diff --git a/make_cdd.py b/make_cdd.py
old mode 100644
new mode 100755
index 396769d..528ccbd
--- a/make_cdd.py
+++ b/make_cdd.py
@@ -1,3 +1,4 @@
+#!/usr/bin/python
 """
 Utility for building the CDD from component markdown files.