Support for downloading operator LPs using swiftclient

[Murali Allada]

See the following thread for dev list discussion:
http://lists.openstack.org/pipermail/openstack-dev/2015-June/067340.html

Operator LPs only accessible using a public url today. We currently 'wget' these LP images while building a users application image on top of the operator LPs.

This works fine with small images, but as docker images get larger, I've noticed the images get corrupted due to network issues and not downloading the images in chunks.

We need to also want to support downloading the LP images from a swift container belonging to the service operator using a swift client. Swift has already implemented retry logic, downloading in chunks and it faster as well.