Support phobos mput/mget functions
Phobos command line has functions for dealing with mutliple files at once. Those are handled in the c functions as a parameter that is currently always set to one.
S3 also has a functionality to send/recieve mutiple files at once.
I propose to check if it is only a convenience to send multiple files or if it generates a performance boost. If it does and if we want to support that functionality from S3 (issue #16 (closed) ), we should update phobos_file to handle more than a single file at a time.