README will be improved soon
Sorry, no time to do much more with it just yet.
This is related to the SaltConf18 presentation available here,
This custom hack on the standard modules/s3.py allows calls to s3.put to define custom headers.
This permits setting HTTP headers which in turn can be used to set S3 object metadata, including the HTTP Content-Type.
You want this if you want to say, set a HTML file sent to S3, as actually being Content-Type: text/HTML
The default is binary/octet-stream and this is what is currently set for any objects created using s3.put