cli: indicate success for all commands #444

Currently some of the commands, especially simple ones like sysand info, produce no output on success, making it unclear if the command succeeded. All commands should indicate success, just as they indicate failure through errors.

It seems that only info commands don't produce any output and don't indicate success. All other commands either produce the requested output (e.g. print-root), or indicate that the action was successful (e.g. remove).