Better AWS S3 path handling

[nvnieuwk]

In the newest version, the AWS S3 path handling will be disabled by default because it was causing error messages like this one:

ERROR ~ The AWS Access Key Id you provided does not exist in our records. (Service: Amazon S3; Status Code: 403; Error Code: InvalidAccessKeyId; Request ID: D5F3ZK64NNE9F037; S3 Extended Request ID: KYI+/3lvyGlGrOU2XGMc2BSD4t7ZIN+KIe7+uecUoVCA166mOidD7khmutQL5dj8Y5Ahi0rzhw2NZCuIwcU/kg==; Proxy: null)

These say absolutely nothing of what the problem is (in this case the bucket wasn't found in the s3 endpoint). We should add some better handling to detect these kind of problems and give a better error message