Staccato image transfer project.

Adding the image transfer service project.  This project can be used
by OpenStack components to transfer VM images (or other large dataset.
Use cases include:
- downloading images to nova compute nodes
- broadcasting out images for large virtual cluster boots

More details can be found here:

blueprint: image-transfer-service

Change-Id: I32b633ab3fb3a5fcafb4e25fd7f9ea52770f092c
Reviewed-on: https://review.openstack.org/34822
Reviewed-by: Clark Boylan <clark.boylan@gmail.com>
Approved: Jeremy Stanley <fungi@yuggoth.org>
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Tested-by: Jenkins