Change the APS S3 implementation to be a overwriteable spring bean

Summary of Enhancement/Business Case
The way APS currently works, the S3 implementation in APS is instantiated internally only.

Can we make a change to the product, so the S3 implementation is registered as a spring bean, which could be overridden? This would allow a custom S3 client implementation to be provided. Customers would then be free to use whatever implementation they want. Customer is looking into an option to use client side encryption and does not want to pass user name and password, so this would be possible using their own overwritten spring bean.

Additional Information

• http://docs.aws.amazon.com/sdk-for-java/v1/developer-guide/examples-crypto.html
• http://docs.aws.amazon.com/kms/latest/developerguide/crypto-intro.html