Updated openstack/openstack
Project: openstack-dev/devstack  1dde567e75a08d634e090a8e3d972890c7438530

Use Mongo DB as the default backend

With the gate upgrade to Trusty, Marconi should now be able to run with
Mongo DB at the gate.

Change-Id: I7bfe25d42c9429606ee209860685077806eb6756