change file encoding back to ascii

Fixes:

SyntaxError: Non-ASCII character '\xe2' in file /usr/share/openstack-dashboard/op
enstack_dashboard/local/local_settings.py on line 224, but no encoding declared;
see http://www.python.org/peps/pep-0263.html for details

Change-Id: Idde6845129505cdec775fcdaa3199be4f79ae41d