Work around a swift bug when downloading the akanda image from DHO.

Newer versions of swift have a bug that prevent output from being
streamed to stdout (https://bugs.launchpad.net/bugs/1395922).  Work
around this by saving the LATEST pointer file in /opt/stack and reading
its contents.
Merge pull request #10 from ryanpetrello/master

Work around a swift bug when downloading the akanda image from DHO.