feature request: ACL transform

[clshortfuse]

First, I would like to thank you all the hard work you've done. It's extremely useful for my needs.

I have one issue wherein I don't want all files to be uploaded to the bucket with the same ACL type. Specifically, I'm using an S3 bucket for web pages (and then using Cloudfront to serve the page).

I would like to include .map files but I would want the files to be private instead of public-read. If there were some sort of translation I could perform based on the filename/keyname, that would easily solve my issues. For the time being I'm going to try to use multiple pipes.