Updated openstack/openstack
Project: openstack/sahara  53e7d93ae4207d6469960af0482b0c65ffc577fd

Sync the latest DB code from oslo-incubator

Update includes a lot of changes from oslo. Previous update was
on Dec 9, 2013.

Sahara code changed because of oslo.db API change.

The main change in API is that oslo.db no longer stores SQLAlchemy
Engine and sessionmaker instances globally and it's up to applications to
create them.

Change-Id: I3e90739ab96fa8c4c718f22542df8460cb052ad9