Add possibility to use compatible S3 implementations

[tobilg]

Currently, it only seems to be possible to specify the S3 region, access key and secret key, meaning that only the original S3 can be used.

To be able to use S3-compatible implementations, such as Ceph's Rados-Gateway, one would need to be able to specify the endpoint URL (protocol, IP or FQDN and port).

For the Ruby SDK, I only found this: http://docs.aws.amazon.com/sdkforruby/api/Seahorse/Client/Plugins/Endpoint.html whereas the JS SDK has apparantly more details at http://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/Endpoint.html

[tobilg]

Closing due to no reaction