Installation doc setup.py

The setup.py is not executable and does not contains #! sign at the
beginning.

Change-Id: I6f3aa542eb883ade0650a33f31a8b5ffaff9a615
Reviewed-on: https://review.openstack.org/32318
Reviewed-by: Monty Taylor <mordred@inaugust.com>
Reviewed-by: Antoine Musso <hashar@free.fr>
Approved: James E. Blair <corvus@inaugust.com>
Reviewed-by: James E. Blair <corvus@inaugust.com>
Tested-by: Jenkins