Fix testproject/manage.py to be executable

testproject/manage.py could not be run as ./manage.py because
shebang was not the first line. Thus, the import commands raised
errors. Obviously, "python manage.py" worked but now even short
"./manage.py" works.

testproject/manage.py

+#!/usr/bin/env python
 from __future__ import absolute_import
 from __future__ import unicode_literals
-#!/usr/bin/env python
+
 import os
 import sys