Added support for symlinked directories.

I had a problem in s3_website in that the push command didn't follow symlinked directories. I followed the trail back to here, and this seems to have fixed it. The change I made was found on Stack Overflow: http://stackoverflow.com/questions/357754/can-i-traverse-symlinked-directories-in-ruby-with-a-glob

I am not fluent in ruby, but this seems like a pretty small change.