fopen s3 objects directly to work around unexplainable guzzle bug

For some reason when a text file started with a valid hex character ([0-9a-f]) it would eat the text untill the first newline
The new code does basically the same thing as guzzle/s3-sdk did only without wrapping everything in a guzzle stream

Signed-off-by: Robin Appelman <robin@icewind.nl>