Skip unexpanded stubs during clean
Fix error in README
Fixed scp.rb using both spaces and tabs for indentation
Fixed files with zero size were treated as deleted
Tiny output changes tweaks
Added error handling for downloading files from S3
Implemented 'autodownload' setting. Fixed an edge case.

If a file had been added before git-media was added to the repo and
it had a line break after exactly 64 bytes, it could be stripped by
the smudge filter.