Restore printing of Snap URL and use a mirror that does not use

HSTS.  With a https Snap URL Firefox refuses to load the bits from
our (http) python server.  The proper fix would be to get
snap-ev3.py to support https.

snap-ev3.py

@@ -49,5 +49,6 @@ print "Starting listener on EV3"
 os.system('scp listen.py %s@%s:' % (EV3_USER, EV3_IP))
 #os.system('ssh %s@%s -- nohup python3 listen.py %d &' % (EV3_USER, EV3_IP, EV3_PORT))
 
+print ('http://cs10.org/snap#open:http://localhost:1330/snap-ev3')
 httpd = TCPServer(("", SNAP_PORT), Handler)
 httpd.serve_forever()