Move s3 access & secret key and endpoint directly to the configs

[snosratiershad]

Hey, I don't understand why S3 endpoint and credentials should be stored in files. I think we should make them directly loaded configs

[skariel]

it is this way so there can be default configs in code. but it might be better to remove this code, and consolidatie all configs in a single file. then we can commit an axample json config. it will be simpler

[wizardishungry]

Consider removing the credential part of the code from the config file. The clean way to load AWS credentials is to use config.LoadDefaultConfig which allows you to put the credentials in idiomatic environment variables or ~/.aws/credentials, etc.