setup: Defaulting to python3

On systems where both python2 & 3 are installed, its better enforcing python3.

If python points to python2, hardware-detect fails with the following message :
	-bash-4.2# hardware-detect
	Traceback (most recent call last):
	  File "/usr/bin/hardware-detect", line 6, in <module>
	    from hardware.detect import main
	  File "/usr/lib/python2.7/site-packages/hardware/detect.py", line 34, in <module>
	    from hardware import areca
	  File "/usr/lib/python2.7/site-packages/hardware/areca.py", line 99
	    def _run_and_parse(*args, rev=False):

Let's default to python3.

Signed-off-by: Erwan Velu <[email protected]>

setup.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 # Copyright (c) 2013 Hewlett-Packard Development Company, L.P.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");