Changed amazon s3 adapter to create a real directory

I was looking and found a way to create a directory like you can with the AWS S3 site using the S3 client and found a way. The way to do it is to make sure there is a ending `/` at the end of the path when calling `putObject` with an empty string.

![screen shot 2014-03-11 at 1 21 36 am](https://f.cloud.github.com/assets/207171/2382486/c2dfa3a0-a8e5-11e3-8155-8eae3c039910.png)

What do you think @FrenkyNet?