Move to python3

This commit moves configure.ac and python scripts to
python3

Signed-off-by: Santosh Puranik <santosh.puranik@in.ibm.com>
Change-Id: Iaa03dffe15903fbd68c354442823903cc3bb3ad2
diff --git a/extra-properties.py b/extra-properties.py
index 728fc14..f0f195c 100755
--- a/extra-properties.py
+++ b/extra-properties.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 import os
 import yaml