Updated openstack/openstack
Project: openstack/heat  a550ac0307f22426a00b265ca8c1d09f5103182c

Move network constraint to neutron plugin

This allows exception imports to be encapsulated inside the neutron
plugin, and plugins are likely the most appropriate place for
custom constraints to live.

Change-Id: I5766edb305b7cfffdcd8943fb6edce7f3e9ff26d