Added directory permissions to improve SFTP compatibility

[thomascollett]

POSIX permissions must be sent back to the sftp client for directories in order to cd to a directory.

This change uses the bucket ACL as a proxy for directory permissions (since directories aren't actually objects in S3, so do not have their own ACL).

Fixes #94

[carlspring]

Hi @thomascollett ,

I hope you're well!

I'm not sure, if you've recieved my e-mail, but just in case -- I'm reaching out here as well. As this project seems to have been abandoned, I was wondering, if you'd be interested in contributing these fixes against our spin-off (rebranded fork) -- s3fs-nio?

Kind regards,

Martin

[carlspring]

Hi,

@thomascollett , we would like to thank you for your work on this and are sad to see that it was not accepted and merged in this project!

However, for anyone interested, we've used this as inspiration of how to implement it in our spin-off (rebranded fork) -- s3fs-nio where we have now also migrated our code to AWS SDK v2 (see carlspring/s3fs-nio#63) . As this upstream is now clearly dead (#135), please feel free to check out our work in carlspring/s3fs-nio#146 where we have already implemented these changes.

We would like to rebuild a community around the s3fs-nio and would be thrilled, if you'd like to join us in our efforts to build a stable library that is well-maintained, documented and regularly released.

Kind regards,

Martin Todorov