respect the virtualenv by using /usr/bin/env

Signed-off-by: S.Çağlar Onur <caglar@10ur.org>
diff --git a/planetstack/core/tests.py b/planetstack/core/tests.py
index d07069a..a02497e 100644
--- a/planetstack/core/tests.py
+++ b/planetstack/core/tests.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 from django.test import TestCase
 from core.models import *
 from rest_framework.test import *