Proxy

Had some problems with using a proxy while uploading code through the grunt-aws-s3 module, apparently the proxy at our company was trying to use the aws secret in the Authorization header as the proxy credentials which of course always fails and results in a http 407. This seems to be fixed if the Proxy-Authorization header is set with the actual proxy credentials. Not entirely sure but it could be that these issues are related and possibly fixed:

https://github.com/aws/aws-sdk-js/issues/108
https://github.com/aws/aws-sdk-js/issues/26