Remove setBucket() function

Remove the setBucket function/ discuss its removal. Currently the name for the bucket is extrated from the GET request (it is in the form of GET bucketname/key) and then saved as a metadata to phobos. Depending on how much of the buckets we want to implement (this is the discussing part) we might want to reduce complexity here and just use the complete string (bucketname/key) as objectID for phobos.