Fix issue #225 by using python3 in the shebang instead of python in...

Fix issue #225 by using python3 in the shebang instead of python in faust_data_downloader.py (pyfaust.datadl).

misc/faust_data_downloader/faust_data_downloader.py

-#!/usr/bin/env python
+#!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 from __future__ import print_function