Add logging

Different kinds of log files might be set up on the server.

One possibility is to add general log files on the server level for all request that come in.

Another is the S3 approach where logging can be activated on a bucket level ( dependent on issue #53 (closed) ) and then all executed tasks on that bucket and its objects are logged (who does what and when). Documentation for this can be found here: https://docs.aws.amazon.com/AmazonS3/latest/dev/ServerLogs.html

The main difference is that the user has access to the second type of logs, where in the first case only the server maintainer can access them.