Define endpoint to use other s3 compatible object storage

[Kiina]

There are a lot of s3 compatible object storages out there, like minio and co. But there is currently no option to define your own endpoint which could be used instead of the amazon one. While I'm not to familiar with the official AWS sdk it looks like you can define it and expose it as a config to the users. This would make this plugin usable for many a lot more situations.

[mikehazell]

Hi Kiina, this is an interesting idea. Would you like to test this out in a fork and make a PR if you find it does work. This option would need some clear documentation around it, why it exists, any caveats etc.