Following up on the thread i posted earlier your patch solved one issue but not all issues with the error.
I've spoken with aws support and it seems that the new error i get is due to the fact that eu-central-1 uses
a new SignatureV4 method and foreman doesn't know it yet.

Here is error i get now :

Warning!
AuthFailure => AWS was not able to validate the provided access credentials

Here is the aws help i got :

The eu-central-1 region support on the SignatureV4 method, you need to update your SDK/CLI to the latest version.

Here you can find our documentation on the new Frankfurt region and the signature:
http://aws.amazon.com/blogs/aws/aws-region-germany/
http://docs.aws.amazon.com/general/latest/gr/signature-version-4.html

Here for you convenience you can find the links to the SDKs and CLI Tool:
http://aws.amazon.com/tools/
http://docs.aws.amazon.com/cli/latest/userguide/cli-chap-getting-set-up.html