Upload Djblets releases to Amazon S3.
We're now using Amazon S3 to store all our releases. This updates our

release script to do that. It requires our new 'fabazon' module to help

interface with S3 and perform S3 uploading and directory index

regeneration.

Temporarily set the destination to be inside a temp directory, and turned

off things like release registration. Ran the script, and saw that there was

a browseable directory of releases on the bucket.