Updated openstack/openstack
Project: openstack/neutron  1e1640565088c444acf6fd2ab66b87b6aa339f7a

Removed signing_dir from neutron.conf

The default value from keystone middleware ($TMPDIR) is good enough,
so stick to it.

Closes-Bug: 1313780
Change-Id: Ideb393f9010f4f1706392ccdfdd5fa7307bda070