Updated openstack/openstack
Project: openstack/nova  2f9fa97e4c7365b8e7b2e89a57d91eb70c03c315

Use EC2SnapshotMapping for creating mappings

Use the EC2SnapshotMapping nova object to create the mappings instead
of using the db api directly.

Part of blueprint convert-ec2-api-to-use-nova-objects

Change-Id: If280b1061185faf71c632a7bc4a8530346c18c97